An afternoon hike takes us under an emerald canopy of aromatic hardwood trees and thick vines perfect for a Tarzan swing. A waterfall has carved out a swimming hole where we can cool down. Jungle scents and mist rainbows fill the air. Towering limestone rocks and cliffs inspire climbing, providing an excellent view of the rainforest and its denizens.

Over 200 bird species nest there, including the prehistoric tropical hornbill, looking like a bird of paradise flower taking flight as it glides beside the cliffs.

The next day brings another adventure: We hike to a remote river that disappears into the mountain. For 45 minutes, we follow the cave through the rock. Curtains of white stalactites glisten when we shine our flashlights onto the wall. A family of bats, hanging upside down from the cave ceiling, silently watches our passage. There are sharp bends to negotiate, a narrow crevice ... and at last we see light shining through at the other end.

Khao Sok National Park is also home to the rare Rafflesia, the world's largest flower. It's also the most foul-smelling, according to those who have witnessed its once-a-year blossom, a flower 30 inches across — big enough to dwarf a basketball.

And now, our group moves on to Thailand's biggest island, with more great hiking, sandy beaches, nightlife, and some memorable sea canoeing: The island of Phuket.

Other stops on this tour of Thailand:

Bangkok | Chiangmai | Hill Tribes | Phuket