Tucked in the limestone cliffs and lush vegetation in southern Thailand lies a spot with no roads and enough activity to make any adventure traveler salivate. Rai Lay, in Krabi Province on the west coast, is renowned in the rock climbing world for its numerous bolted sport routes and pocketed rock. Snorkelers and scuba divers journey here for the warm water, 30-meter visibility and the chance to glimpse the gargantuan whale shark. Sun worshippers come for the long white beaches and tropical heat. Culture seekers search out the 1,272 steps of the Buddhist temple Wat Tam Sua, the cave paintings in Tam Lod Caves, or the fire show performed on the beach by the friendly locals. However, any traveler who comes to Rai Lay and misses the two short but infamous hikes would be missing a true adventure.

As we eat breakfast on Sunset Beach and gaze at the gaping black cave opening on Thaiwand Wall, we overhear some travelers talking about their encounter on the way to Phra-Nang beach. They had come upon some monkeys swinging serenely in the trees and walking closer for a better look, they made eye contact and smiled as they approached. The monkeys apparently mistook the smiling for the baring of teeth and the eye contact as a challenge to fight. They swooped down from the trees and like bandits grabbed at the travelers' bags. After a vicious game of tug-of-war, the travelers won and ran from the trees clutching their possessions. To get to the beginning of the cave hike, we'll take the same path.

Once on the path, we walk tentatively and sure enough, around a corner, we meet a dozen pairs of eyes. We make sure to frown, look at our feet, and shuffle past them. Thus, just getting to the start of the hike can raise your heart rate. Phra-Nang beach deadends into a bamboo forest with towering crags. The limestone stands ominously — a cornucopia of stalactites and black holes. We reach the cave opening, as big as the hull of a ship, and with bats flying in and out overhead. The Thais call this crag "Khao Luk Choee," or Grave Marker of the Bat Man, after a man who was killed by falling rock while gathering guano. Some easy bouldering takes us in to the mouth of the cave and the true beginning of the hike. Inside, the light dwindles, but keyhole cracks in the soft stone allow peeks of the Andaman Sea. As we walk deeper into the cave, the light disappears and we rely on our headlamps which can illuminate only small portions of the inner sanctum rock. The acoustics change and everything echoes, especially the chirps of hundreds of bats upset at the disturbance.

We come to our first fixed bamboo ladder, put in and maintained by the local climbing community. The rungs, woven by rope, squeak under our weight as we make our way slowly over the deep black holes. It's like climbing in the dark upon a warm glacier and placing your trust only in hollow wood to hold you above the crevasses. With some route finding, we climb several more ladders until a stream of light creeps like water and finds its way around the rock.

We've now hiked through the middle of the monolithic Thaiwand Wall from one bay to the other. West Rai Lay Bay, our breakfast spot, sits far below us now and, from our height, the longboats look like a kid's toy model. A bolted anchor sits to the right of the cave opening, allowing us to rappel down to the cave hike finale. After the combination spelunking-hiking-fixed-ladder-climbing, it's easy to bushwhack through the thick rainforest back to sunset beach.

Clouds creep in one morning but we plan on chancing the rain and completing the Lagoon hike. The lagoon is a freshwater lake surrounded by jungle and tucked away between two limestone pinnacles on the southern side of the Phra-Nang peninsula. We strap up our sport sandals, pack some water and head to the trailhead. Starting off ruthlessly steep, we scramble up over exposed roots and sharp rocks to reach the first fixed rope. Each rope brings us deeper into the jungle while, around us, frogs and birds contribute to the cacophony of jungle noise. With full-body effort, we haul ourselves up the ropes to our first viewpoint of East Rai Lay Bay.

Then the rain starts though Jurassic Park-like leaves shelter us from the warm drops as we continue towards the lagoon. The soil dampens and our grips tighten on the braided ropes. And then, with monsoon meanness, the sky opens up. We are finally forced to turn back, not wanting to abandon the lagoon, but unable to continue over the slick and oily red clay beneath our feet. Our toes collect mud and we occasionally slip as if sliding into home plate as we descend rope after rope. We aren't smiling as we lower ourselves down python-sized roots and blocks of limestone in this rainstorm that has reached epic proportions. But when we reach the trailhead, our skin and clothes red with clay, we laugh the hysterical laugh of an adrenalin rush mixed with relief.

Low season in Rai Lay runs May through October and in this time, the monsoon-like weather is always a possibility. However, the bungalows are easy to find and cheap to rent. You don't need much luggage and generally sport sandals will do for adventure hikes. (Flip-flops should be reserved for the seasoned traveler.) You can reach Rai Lay by plane, train, bus or boat. The quickest route from Bangkok is a 70-minute flight to Krabi, followed by a 50-minute longtail boat ride.

— Krista Crabtree, MountainZone.com Correspondent