HONOLULU — It would be an arduous 2,000-foot climb up more than 3,500 metal steps anchored into a lush green cliff in Oahu's Koolau Mountains.

On the nicknamed "stairway to heaven," hikers literally climb into puffy white clouds over a tropical forest for views of the Haiku Valley and beyond, to the ocean.

But those who try the Haiku Trail risk a trespassing ticket and a towed vehicle. The trail is closed to the public by the private land owner at the base of the stairs, even though the island government spent $875,000 in 2002 to make repairs.

Fortunately, even though this and a few of Oahu's other finest trails are off-limits due to access issues or rock slides, there are another 80 trails to choose from.

A system of nearly 20 paths in the Koolau Mountains above Honolulu wind through the thick canopy of the rain forest and lead to some of the highest ridges that overlook deep vistas and lush valleys. Others take explorers to hidden waterfalls or introduce hikers to the variety of native plants and wildlife.

For many, it's an escape from crowded Waikiki, now lined with luxury shopping and fine dining.

"These trails have been the most redeeming part of our trip," said Dan Lemley, 26, of Portland, Ore., who trekked to Manoa Falls above the University of Hawaii's main campus and then climbed up the steep, muddy Aihualama Trail.

"Since we've been here, we have been appalled at the tourism and lack of Hawaiian culture. This hike made us just stand back and say, 'Wow!"'

Getting to the beaches is easy, but the trails wend deep into the real beauty of Hawaii, with crooning birds, endless varieties of plants and greenery — all while offering a sweaty workout.

Hiking in Hawaii has gained popularity in the past few years with the availability of more guidebooks and comprehensive Web sites, said Aaron Johnson Lowe, Oahu trails and access specialist for Na Ala Hele, which maintains and manages the trails for the state.

Lowe said there seems to be a trend of people looking for more healthy activities, and he's also noticed many repeat visitors who have done the tourist activities are now wanting more from the island.

"It seems once they get on one trail, they become hooked," he said.

A brief warning: Watch out for pig hunters, who sometimes use the trails, and check online if permits are required for certain hikes.

Based on hikes of more than 30 trails, here are some of the best:

• One of the most popular hikes on the island takes visitors inside Diamond Head volcanic crater, where even relatively unfit travelers can trudge up 175 stairs and journey through a 225-foot unlit tunnel to reach an observation deck once used by the military to search for approaching enemies. The paved trail attracts novice hikers rewarded with a view of the shores of Waikiki and nearby areas from above.