Forrest Brown and Brekke Fletcher, CNN

(CNN) -- Once one of the world's most powerful travel documents, the might of the United States passport has been diminished during the pandemic. With US Covid-19 cases now past the 32.4 million mark, some nations continue to view vacationers warily even as more Americans get vaccinated.

In the end, it's up to you to decide whether travel to international destinations is a good idea. The health risks are obvious. Variants of the virus have emerged. Nations might change their rules at any time. You may have to adhere to strict curfews and mask mandates. Violations could involve big fines and even jail time.

If you want expert input into your decision, the US State Department and the US Centers for Disease Control and Prevention provide Covid-19 risk assessments by country. The CDC rates many of the countries open to US travelers at Level 4, at the highest risk for Covid-19.

Also, keep this in mind: All air passengers 2 and older must show proof of a negative Covid-19 test that's no more than 72 hours old to enter the United States. That includes US citizens returning from trips to other countries. Check here for the latest CDC international travel guidance for fully vaccinated people.

What follows is an alphabetical list of countries and territories where it's still possible for US passport holders to go for a vacation. The most recently added information is in bold type for faster scanning:

Albania

Set on the Adriatic Sea, Albania remains open. While there's no Covid-19 test requirements or quarantine to enter, expect a health screening. More info: US Embassy.

Antigua and Barbuda

US travelers 12 and older to Antigua and Barbuda arriving by air must present a negative Covid-19-RT-PCR (real time polymerase chain reaction) test result, using a nasopharyngeal or oropharyngeal swab. It must be taken within seven days of the flight.

Visitors are subject to monitoring by health officials for 14 days and another Covid-19 test may be required, which could mean quarantining while waiting for the result. More info: US Embassy | Antigua and Barbuda government website.

Armenia

From the historic capital of Yerevan to wild national parks, Armenia is open to US tourists. To enter, you are asked to have a negative result from a Covid-19 test taken within 72 hours of arrival or take a test upon arrival for about $40 and self-quarantine until you get your result. More info: US Embassy | Armenia's official Covid-19 travel website.

Aruba

Scroll down to the "Dutch Caribbean" entry below for information on Aruba and other islands in this group.

The Bahamas

UPDATED: Visitors 11 and older must have a negative Covid-19 PCR test result no more than five days old before arrival. Once you have the negative result, you can apply for a Bahamas Travel Health Visa here. Fully vaccinated travelers must upload proof of inoculation and are exempt from testing starting May 1. All travelers must opt-in to Covid-19 health insurance; the cost is included in the health visa fee. Get updates: US Embassy | Bahamas' travel website.

Barbados

UPDATE: New protocols are slated to start May 8; click this link to learn more. Until then, US citizens must complete an online travel form and submit it 24 hours before leaving. You must present a valid negative Covid-19 PCR test result, taken within 72 hours of arrival. All travelers must take a rapid antigen test on arrival.

As the US is designated a high-risk country, you must still quarantine at an approved hotel or resort until you get a second test and negative result. The quarantine is a minimum of five nights. You must also wear an electronic tracking bracelet. More info: US Embassy | Visit Barbados website.

Belize

UPDATE: To enter this Central American nation, you must download the Belize Health App and input your information no more than 72 hours before arriving.

You can bring an official vaccine card reflecting that you've gotten inoculated at least two weeks before arrival. Otherwise, have a negative Covid-19 PCR test result taken within 96 hours of arrival or a rapid test within 48 hours of arrival. Or you can be tested upon arrival at a cost of $50. You must have proof you've booked a room at a gold standard hotel. More info: US Embassy | Belize Tourism Board.

Bermuda

This Atlantic island requires each inbound passenger 10 and older to apply for travel authorization at the cost of $75 per adult and $30 for flight crew and children 9 and younger. Upon arrival, passengers must present a negative Covid-19 PCR test result taken no more than five days before departure.

You'll be tested again at the airport and quarantined while waiting for those results. More tests are required on days four, eight and 14 of your visit. Click here for specific instructions for immunized travelers. More: US Embassy | Bermuda Tourism Authority.

Bolivia

This landlocked South American country of wildly varying landscapes allows US visitors but has recently tightened requirements. To enter, those 6 and older must have a negative Covid-19 RT-PCR test taken within 72 hours of departure. Expect a health screening. You must quarantine for 10 days and take another PCR test on day seven. More details: US Embassy.

Bosnia and Herzegovina

US citizens may enter Bosnia and Herzegovina, known for cosmopolitan Sarajevo and gorgeous lakes, with a negative Covid-19 PCR test result that's no more than 48 hours old. More info: US Embassy | Bosnia Border Police

Botswana

US citizens can enter this safari favorite with a negative Covid-19 PCR test result taken no more than 72 hours before departure. If you fail to provide test results or show coronavirus symptoms, you will have to quarantine for 14 days at your own expense. Expect "inconsistent application of rules" or sudden changes in policy. Learn more: US Embassy.

Brazil

UPDATE: South America's largest country continues to have very high number of daily cases of Covid-19. The US State Department has it at a Level 4 Travel Advisory (do not travel). If you still choose to go, you must fill out a health declaration and present a negative Covid-19 PCR test result taken with 72 hours of boarding the flight. Be sure to read about the requirements for various ages. Get details: US Embassy.

British Virgin Islands

UPDATE: US citizens need a travel certificate that you can get at the BVI Gateway website. There's a $175 entry fee. You need a negative Covid-19 test result taken five days or less before travel to enter. You'll also get another test on arrival and quarantine four days. You must also test again on day four. More info: US Embassy | BVI government website.

Colombia

All arriving passengers to Colombia should either have a negative result from a Covid-19 PCR test taken no more than 96 hours before departing; take a test upon arrival and quarantine while waiting for a negative result; or go into mandatory isolation for 14 days. Find out more: US Embassy | Colombia's travel website

Costa Rica

US visitors must complete a health pass form but are not required to take a Covid-19 PCR test. You must have proof of travel medical insurance, which you can get in Costa Rica. More details: US Embassy | Visit Costa Rica website

Côte d'Ivoire (Ivory Coast)

US citizens must have a negative Covid-19 PCR test result no more than five days old before arrival. You must fill out a travel declaration form and pay the fee online. You're encouraged but not required to quarantine for two weeks. Learn more: US Embassy.

Croatia

UPDATE: Croatia is once again open to US leisure travelers. You must do one of the following to enter: 1. Provide proof of a negative result from a Covid-19 PCR test that's no more than 48 hours old upon arrival. 2. Provide a certificate of full vaccination. 3. Provide a medical certificate that you have recovered from Covid-19 in the past 11 to 180 days. 4. Take a PCR test immediately upon arriving and self-isolate until getting a negative result.

You must also fill out an official entry form and have proof of accommodation paid in full and advance. More details: US Embassy.

Cyprus

NEW: Both parts of this politically divided Mediterranean island are open to US tourists. The Republic of Cyprus and the northern third of the island administered by Turkish Cypriots (Turkish Republic of Northern Cyprus) each have their own rules of entry and testing. Get all the details here: US Embassy in Nicosia | Visit Cyprus

Dominica

UPDATE: This Eastern Caribbean island is open. All travelers must present a negative Covid-19 PCR test result taken 72 hours before arrival. You must fill an electronic Immigration and Customs form via Dominica's online portal 24 hours before traveling. You must take a rapid test upon arrival. The US has deemed the island a high-risk country. You must book and stay at a "Safe in Nature" certified property and take another PCR test on day five. More info: US Embassy | Discover Dominica.

Dominican Republic

UPDATE: All arriving and departing passengers must fill out an electronic entry and exit form; it can only be in digital form. Covid-19 tests aren't required, but Dominican Republic authorities will give breath tests to a small percentage of random passengers plus anyone showing symptoms.

The Dominican Republic Ministry of Tourism now offers free viral antigen testing to all international visitors staying in hotels. The US Embassy says PCR test results have been reliably available within 72 hours but could be affected by increased demand. More info: US Embassy | GoDominicanRepublic.com

Dubai

Scroll down to the United Arab Emirates entry below.

Dutch Caribbean islands

Find out the important details on these various Dutch islands in the Caribbean by clicking on the links:

Aruba: All US visitors 15 and older must fill out a health assessment and have a negative Covid-19 test result. JetBlue passengers can take an at-home, saliva-based test. You must fill out an embarkation and disembarkation card and purchase Aruba Visitors Insurance. More info: Aruba's official tourism site.

Bonaire: You must fill an online health declaration form. A negative result from a Covid-19 test is required to enter. Find out more on the tests and other details: Bonaire Crisis.

Curaçao: All US visitors must present proof of a negative Covid-19 PCR test result taken within 72 hours of traveling. You must fill out a digital immigration card and passenger locator card at dicardcuracao.com. People from high-risk countries, which includes the United States, must take a rapid antigen test on day three of their visit. A curfew is in effect that tightens tourist activities. More info: Traveling to Curaçao | Curaçao news bulletins.

Sint Maarten: An autonomous country within the Kingdom of the Netherlands, Sint Maarten shares an island with the French collectivity of Saint-Martin. To visit Sint Maarten, US visitors must fill out a mandatory health authorization application. You must also have a negative result from a PCR for Covid-19 taken within 120 hours or less or from an antigen test that's taken with 48 hours of departure. Covid-19 health insurance is mandatory.

Get more US consulate information on all these Dutch islands by clicking here.

Ecuador

Travelers 3 and older must have proof of a negative Covid-19 PCR or rapid antigen test taken within three days of arrival to avoid quarantine. Or you can present a completed vaccination card. Testing is available for those who don't arrive with a negative result. You must quarantine at an approved facility while waiting for results. The US Embassy suggests you advise a lab that you need test results within 72 hours for your return flight to the US. The Galapagos Islands have additional entry requirements. More info: US Embassy.

Egypt

US travelers to Egypt need to present a negative PCR Covid-19 test result. Carefully read the US Embassy's advice on the timing of the test -- from North America, it should be no older than 96 hours before flight departure. Travelers must present paper copies; digital copies aren't accepted. Children 5 and younger are exempt. You may be required to show proof of health insurance. You may travel to the Red Sea resort town of Sharm el Sheikh without a PCR test, but you must be tested upon arrival and quarantine until you get a negative result. Details: US Embassy.

Ethiopia

Ethiopia requires arriving US citizens to have a medical certificate with a negative Covid-19 PCR test before boarding their flight that's no more than 120 hours old. There's also a seven-day quarantine. Before you travel there, closely monitor news reports about human rights abuses and killings in the northern Tigray region on the border with Eritrea. More info: US Embassy.

French Polynesia

NEW: After a closure of several months, travelers are welcome to come back to the South Pacific islands of Tahiti on May 1. French Polynesia requires a negative Covid-19 test result within 72 hours of departure, to be presented before boarding. You must fill out an online ETIS form before you go.

If you are vaccinated, you need to present proof of your CDC card into ETIS. If you got a Pfizer or Moderna shot, you can travel the day of your second shot. If you got Johnson & Johnson, you must wait 14 days to travel to French Polynesia. Travelers who caught Covid-19 but are recovered can enter with a serological test that shows a positive test for antibodies. Upload proof to ETIS with a doctor's note. Non-vaccinated or naturally immune travelers will be required to quarantine for 10 days, even with a negative test result. Get more important details: Islands of Tahiti | FAQ document

Georgia

US travelers can visit Georgia, a geographical and cultural crossroads at the Caucasus Mountains. Fully vaccinated people can enter with documentation. Otherwise, you need to complete an application form and show negative results from a Covid-19 PCR test result taken within the past 72 hours. You'll need to get a follow-up test on your third day. More: US Embassy | Ministry of Foreign Affairs

Ghana

This West African cultural jewel is open US travelers. You must have a negative result from a Covid-19 PCR test taken no more than 72 hours before departure. Arriving passengers then must take a second test that costs $150. There's also a temperature screening. Details: US Embassy.

Greece

Greece is now open to US travelers who are either fully vaccinated or those with a negative result from a Covid-19 PCR test that's no more than 72 hours old upon arrival. You must fill out an online passenger locator form. Would-be tourists should be aware Greece is still under a lockdown and curfew. More information: US Embassy.

Grenada

UPDATE: This Caribbean island is welcoming US visitors, but they must do the following: Have health insurance that covers Covid-19 illnesses; present a negative Covid-19 PCR test result within 72 hours of departure (for 6 and older); apply for travel authorization with the Ministry of Health; take a second test on day five to be allowed to move about or remain at the hotel for the rest of the vacation. Starting May 1, fully vaccinated travelers have to quarantine for only 48 hours. Details: US Embassy | Grenada's Ministry of Health.

Guatemala

UPDATE: People 10 and older entering Guatemala by air and land must have one of the three following: 1. A negative result from a Covid-19 PCR test or antigen test taken 72 hours or less upon arrival. 2. Evidence of a Covid-19 vaccine completed at least two weeks before arrival. 3. Evidence you've had Covid-19 and recovered in the past three months. You must fill out an online health pass. No quarantine. Travelers who have visited to Brazil, South Africa or the UK may be denied entry. More details: US Embassy.

Honduras

Travel to Honduras is permitted with a negative result from a Covid-19 PCR or serology test. You must also fill out an online precheck form. Travelers who have been to the UK or South Africa must quarantine for 14 days. Learn more: US Embassy.

Iceland

Starting April 6, US travelers who have proof of being fully vaccinated or those with proof of contracting Covid-19 but are now recovered may enter Iceland. This exempts US visitors from testing and quarantine requirements. Important details: US Embassy.

Ireland

US travelers are still allowed to visit, but restrictions on movement could make it a very limited vacation. You must fill out a passenger locator form -- failure to do so could result in fine or even jail time. You must present a negative Covid-19 RT- PCR test result taken within the previous 72 hours to enter. There's a mandatory 14-day quarantine for all arriving Americans regardless of Covid-19 or vaccination status. Additional info: US Embassy | Irish government travel page.

Jamaica

UPDATE: Jamaica requires that you fill out an online travel authorization form. There's the possibility of being tested upon arrival. All passengers arriving from the United States 12 or older are required to upload negative results from a Covid-19 PCR, NAA, RNA or antigen test within three days of the travel date. More details: US Embassy in Jamaica | Visit Jamaica website.

Kenya

UPDATE: Kenya is open to US travelers with a negative Covid-19 test result taken 96 hours or less upon arrival and who pass a strict health screening. No quarantine. Arriving visitors have a QR code and departing travelers must have a TT code from the Trusted Travel initiative. More info: US Embassy.

The Maldives

UPDATE: All arriving tourists who are 1 or older must have a negative result for a PCR Covid-19 test taken within 96 hours of arrival. This includes vaccinated travelers. There is no mandatory quarantine. More: US Embassy | Maldives' official tourism website.

Malta

US travelers with a long vacation and who wish to sidestep the EU travel ban can visit. Passengers who transit via a "safe corridor country" that allows US visitors may enter Malta after they've been in that country for 14 days. For example, US travelers can stay 14 days in Turkey or Ireland and then be eligible to enter Malta. All passengers must fill out Public Health Travel Declaration and the Passenger Locator forms before departure. Details: US Embassy.

Mexico

The land border between the US and Mexico remains closed through at least May 21, but US travelers can still fly there. No testing requirements are in place to enter, but the State Department lists numerous states to avoid because of crime. You can expect temperature checks and other screenings upon arrival. More: US Embassy.

Montenegro

This Balkan nation is allowing US travelers with any of the following: 1. A negative result from a Covid-19 PCR test issued by a registered lab that's no more than 72 hours old upon arrival. 2. A positive result for IgG antibodies not older than 30 days. 3. Proof of a second vaccine dose received seven days ago or longer. Get more information: US Embassy | Institute of Public Health of Montenegro.

Morocco

This North Africa favorite is open to specific US travelers only. You should fly directly from the US as Morocco has suspended flights from many other nations until May 10 under its "Health State of Emergency." You must have reservations with a Moroccan hotel or travel agency or be invited by a Moroccan company. A printed, negative Covid-19 PCR test result taken within 72 hours before departure is required to enter. Expect a health screening. No mandatory quarantines are in place, but local curfews are. Details: US Embassy | Visit Morocco.

Namibia

US citizens can visit this southern African desert nation, which requires a negative Covid-19 PCR or rapid antigen test result that's not older than seven days. If the test is older than seven days, you'll be tested and placed in quarantine at your own expense as you await the results. More info: US Embassy.

Nepal

US travelers can visit the landlocked Himalayan nation. You'll need a negative result from a Covid-19 PCR test taken no more than 72 hours before departure or proof of full Covid-19 vaccination to enter. You'll be tested again upon arrival and must quarantine until you get the results. You'll also need proof you've booked accommodations and proof of travel insurance that covers rescues and treatment. Hikers and mountain climbers have special requirements, including insurance. Find out more: US Embassy.

Nicaragua

Home to historical buildings and tropical beaches, Nicaragua is open. You must have a negative result from a Covid-19 PCR or serology test. No time frame is provided for how recent it must be. More: US Embassy | Avianca Airlines.

North Macedonia

North Macedonia is open. No tests are required. There's no quarantine unless you're arriving via Africa. Airports conduct thermal screenings for all passengers. Details: US Embassy | TAV Macedonia.

Panama

A Covid-19 PCR or antigen test with a negative result, taken 48 hours or less before arrival time, is required to visit Panama. If the test results are older than 48 hours, you must take a rapid Covid-19 test at the airport. You must also fill out an online health affidavit. Cruise ship passengers can't disembark here. More info: US Embassy | Visit Panama.

Peru

Travelers from the United States 12 and older may enter Peru for tourism with a negative result from a Covid-19 PCR test or antigen test or a medical certificate of epidemiological discharge, all no more than 72 hours old. There's still a 14-day quarantine on arrival, but if you test negative on an antigen test once you've entered the country, you can suspend the quarantine. You must also fill out an affidavit of health. More details: US Embassy | Lima airport protocols.

Rwanda

Visitors to Rwanda must present a negative Covid-19 PCR test result, taken within 72 hours of departure. They also must take a second test upon arrival, shelter in a hotel and receive their results within a day. The national parks are open, including primate tracking. To enter a park, you must have a negative test result less than 72 hours old. Additional info: US Embassy | Visit Rwanda

Senegal

Senegal, known for its beaches and music, welcomes US tourists. To enter, all people 2 and older must present an original Covid-19 PCR test certificate with a negative result that was taken five days or less before arrival. There's no quarantine. More: US Embassy.

Serbia

US citizens need to provide a negative Covid-19 PCR test result taken within the previous 48 hours to visit. More info: US Embassy.

Seychelles

These Indian Ocean islands are open. You must show proof of a negative Covid-19 PCR test result taken no more than 72 hours before traveling and have valid health insurance to cover Covid-19 related costs. Vaccination status will not affect entry. You must apply for a travel authorization online. More information: Seychelles Travel Advisory Updates

South Africa

UPDATE: One of the most popular destinations in Africa has reopened to US citizens. You need a negative Covid-19 PCR or serology test result taken within 72 hours of departure to enter. The US Embassy is getting reports of shortages of PCR tests and some results taking longer than the 72-hour window required for the return flight. Be aware some nations aren't allowing entry to tourists who have recently been to South Africa. More: US Embassy.

South Korea

US visitors to South Korea must provide a negative Covid-19 PCR test result taken within 72 hours of departure. US travelers must also quarantine for 14 days upon arrival even with a negative test or full vaccination. You must also submit to health screenings and download a self-diagnosis app with daily reports. More: US Embassy.

Sri Lanka

The tropical island off India's southeastern coast has opened back up to all nations. You must have a negative result from a Covid-19 PCR test to enter, taken within 72 hours of your flight. You must also undergo another test on arrival. Visitors who aren't fully vaccinated must stay at least 14 days at an approved hotel or resort "bio-bubble." Fully vaccinated travelers are free to leave an approved hotel once they get a negative result from the test taken on arrival. More official information: US Embassy | Sri Lanka Tourism.

St. Kitts and Nevis

UPDATE: To visit, you must fill out a travel authorization form before arrival and upload a negative Covid-19 PCR test result taken 72 hours or less before you start your trip. You must stay on approved hotel property for your first seven days. You must take another test on day seven of your visit if you're staying longer. If it's negative, you can move about on a limited basis. For stays of 14 days or longer, a third test is required. Fully vaccinated travelers must submit their record card; they'll have a shorter quarantine and looser restrictions. Additional information: US Embassy | St. Kitts Tourism.

St. Lucia

UPDATE: US citizens 5 and older must provide a negative Covid-19 PCR test that's taken within five days of arrival. Visitors must also complete a travel registration form and arrive with a printed copy. You must have confirmed reservations at a Covid-certified property for the first 14 days. You may leave the resort if your vacation continues. More information: US Embassy | St. Lucia travel website.

St. Vincent and the Grenadines

UPDATE: The recent eruptions at La Soufrière volcano on St. Vincent could make travel to that island difficult or impossible for now. US travelers must have a negative Covid-19 PCR test result taken 72 hours or less before arrival. You'll be retested upon arrival. As the United States is considered a high-risk country, a quarantine of 14 days and additional testing is mandatory. You must also fill out a prearrival form. You can get official Covid-19 protocol documents here. Learn more: US Embassy.

Tanzania

UPDATE: A favorite for safaris and beaches, Tanzania is open to tourists. Incoming passengers are required to fill out a health surveillance form and have a health screening. You might also have to take a Covid-19 test if the airline you're flying with requires it. For return trips to America, the US Embassy says 72-hour results aren't readily available. More info: US Embassy.

Thailand

US passport holders can again visit this popular Asian destination. You must have a negative result from a Covid-19 PCR test no more than 72 hours old upon arrival. There's a mandatory quarantine of 10 days, plus additional testing requirements during your stay. The mandatory quarantine period has been shortened to seven days for travelers who have been fully vaccinated. Get crucial details here: US Embassy | Royal Thai Embassy.

Tunisia

UPDATE: Tunisia is open to US passport holders. You need to complete this online questionnaire before you arrive. You need a negative result from a Covid-19 PCR test taken no more than 72 hours before the start of travel to enter. Starting May 3, you must also quarantine for seven days at a government-selected hotel and then take a second test from day five to day seven. More info: US Embassy.

Turkey

Turkey requires that US citizens 6 years and older have a negative Covid-19 test result taken 72 hours or less before their flight to enter. Passengers must fill out a form for entry and prepare to be checked for coronavirus symptoms. More details: US Embassy.

Turks and Caicos

Visitors must fill out a travel authorization form and provide a negative Covid-19 PCR test result taken within five days of arrival. Children 9 and younger are exempt. Travelers must complete an online health questionnaire and carry travel medical insurance to cover any Covid-19-related costs. More info: US Embassy | Visit Turks and Caicos

Uganda

This lush nation in Central Africa is open to US tourists who have a negative Covid-19 PCR test result taken no more than 120 hours before departure. More info: US Embassy.

United Arab Emirates

Tourist visas for US citizens are being issued at the Abu Dhabi and Dubai airports. Travelers 12 and older must present a negative Covid-19 PCR test result within 96 hours of departure. Even with a negative test, you might still need to quarantine (depending on the emirate) and take a follow-up test. More info: US Embassy.

United Kingdom

Technically, US travelers may still travel to the United Kingdom, but travel for leisure is being highly discouraged. You should closely follow news reports on virus variants and watch for updates on the US Embassy link here before making any plans. If you still choose to go, you must have a negative Covid-19 test result taken 72 hours before departure to enter and quarantine for 10 days. You must fill out a declaration form. Also note that rules may vary between England, Scotland, Wales and Northern Ireland. Click this UK government link for more details.

Zambia

Known for Victoria Falls and wildlife, Zambia is allowing all international travelers to enter. You'll need a negative Covid-19 test result taken at least 14 days before arrival. There's a mandatory 14-day quarantine. The US Embassy has not posted information on the speed of test results for your return to the US. More: US Embassy.

Recently removed from the open list

The following countries had been allowing US citizens to enter but have closed again or were removed by CNN Travel for other reasons:

-- Anguilla: This island's borders are closed until midnight May 6 as it changes its Covid-19 safety protocols.

-- Bangladesh: While technically still open, a flight suspension and lockdown until at least midnight May 5 makes travel there highly difficult.

-- Cambodia: The US Embassy reports the Southeast Asian nation has stopped issuing tourist visas; you can still apply for business-linked visas.

-- Chile: It has closed its borders to almost all tourists through May.

-- Saba: The very extensive entry requirements currently exclude all but a few US citizens from this small Caribbean island.

-- St. Barts: Temporarily closed to all tourists.

Omitted countries

This is a curated list. CNN Travel has omitted certain open countries if they had very limited numbers of US travelers before the pandemic; have ongoing or recent armed conflicts, terrorism or rampant crime and unrest; or have entry requirements so extensive and complicated that they put the country out of reach of almost all US citizens. However, you can click here to check for the status and entry requirements of any country or territory in the world.