By Sara Stewart, CNN

(CNN) -- Let's face it: No matter how long you go for, a trip to Hawaii is always going to feel too short.

For the adventurous, expeditions that combine beaches and hikes can help make the most of your way-too-short travel time in this Polynesian paradise.

Ehukai Pillbox Hike, Oahu

You don't have to be an aspiring Kelly Slater to make a pilgrimage to the reef break at Banzai Pipeline. In fact, it's a lot less life-endangering to keep your feet planted in the sand and watch the monster waves from the shore at Ehukai Beach Park.

Pipeline, on Oahu's North Shore, is one of the world's most famous surf breaks. Its perfect, barrel-shaped waves have made the careers of countless pro surfers -- and claimed the lives of others. It is, quite simply, one of nature's most awesome spectacles.

Yet driving along the meandering Kamehameha Highway, you could blink and miss Ehukai, just one of countless public beaches along this stretch of the shore.

Like most of Hawaii, this attraction wears its stunning natural beauty casually. No big flashy signs, just a tiny parking lot, small bathroom, some wild chickens wandering around, and a pathway down to the 1.2-acre beach.

"I think it's a wave that is really the measure of a surfer's courage," pro surfing legend Shaun Tomson has said of Pipeline, and once you get a look at it, you'll agree.

There are actually several different waves here, created by three successive reefs: The one closest to shore generates the left-breaking Pipeline wave (to the right from a shore-watcher's perspective), and Backdoor, which goes right. Further out, Second Reef and Third Reef can create even bigger surf.

Once you've gotten your fill of wave-gazing (or of the crowds, if it's a competition day), a nearby trail will get you moving but keep you in view of the ocean.

Ehukai Pillbox Hike begins just across the street from Pipeline, in the parking lot of Sunset Elementary school. Head into the driveway and look to your left for a trailhead sign.

Here you'll take the path through a wooded area that begins to climb up steeply, but don't worry -- the trail is only 8/10 of a mile. Along the way you'll stop at a succession of pillboxes, concrete former military lookouts on the hillside facing the majestic expanse of the North Shore.

The path is easy to follow, and you'll eventually find yourself at the summit pillbox, basking in your panoramic view of the ocean. Spending a day here makes it pretty darn easy to follow the instructions spraypainted in neon pink on one of the pillboxes: "GOOD VIBES ONLY."

Kauapea (Secret) Beach, Kauai

At the end of an unmarked street on the north side of Kauai, off Kalihiwai Road, you'll find a wooded path leading to Secret Beach.

The name's a bit misleading, as you'll likely see from the cars in its small parking lot, but Kaupea is still off the beaten path enough that you'll have plenty of space to yourself.

Grab your towel and hike the brief but steep trail downhill; you'll hear the pounding surf to guide you.

A path lined with ironwood trees opens onto a sprawling beach with jagged rocks to the right. At low tide you can hike beyond them and down the beach -- there's a nude section further on, if you're so inclined -- but be sure you know your tides, because the waves come in fast.

How fast? A sign on the trail in warns: "Stay off rocks! Or you're next."

Waimea Canyon hike/Upper Waipoo Falls pool, Kauai

Legend has it Mark Twain crowned this natural wonder the Grand Canyon of the Pacific when he visited Hawaii in 1866. It may be a tall tale, but the name makes sense: At 2,500 feet deep, 2.5 miles wide and 13 miles across, Waimea Canyon is indeed awe-inspiring, and you'll get a good look at it as you drive up to the top for a day hike in.

Canyon Trail, off Halemanu Road, takes you almost two miles down to a broad cliff, where you'll follow the trail over what looks like a dead end down to Upper Waipoo Falls pool. Here, trekkers kick off their boots and hang out in the clear water, with a small waterfall trickling in the background.

You can recharge here for the hike back, which is largely uphill.

Outfitter Kayak Kauai offers a guided Waimea Canyon waterfall hike.

Punalu'u Beach/Ala Kahakai National Historic Trail, Hawaii

Come for the black sand, stay for the sea turtles. At Punalu'u, dig your toes into the charcoal-hued beach and watch the turtles, or honu'ea, make their slow, slow way into the water or genially pop their heads up from the tide pools. Snorkeling and swimming are OK here unless conditions are marked dangerous.

Cross the beach to find a section of the 175-mile ancient Ala Kahakai Trail, which leads up a grassy slope to the remains of a temple, Kane'ele'ele Heaiu, said to be over 1,500 years old. A large flat stone, thought to have been a tablet for human sacrifice, used to mark the entrance (it's now displayed in Honolulu's Bishop Museum).

But you can still follow the trail through countless ancient walls, shrines and mysterious markers. Just remember to be respectful, stay on the path, and never touch or remove anything. You'll come to a natural turnaround point when the trail reaches a fenced-in piece of land.