Detour

GREAT ESCAPE For harried Bangkok residents, serenity awaits a mere half-day drive south at Khao Sam Roi Yot, a marine national park. Despite its proximity to the capital, it harbors isolated coves and a profusion of vegetation-capped, limestone hills (the name means "300 peaks"). Toss in river rafting, and it adds up to Bangkok's best nature getaway.

The park preserves some of Thailand's finest shoreline habitat, as well as sprawling marshes teeming with waterfowl. More than 200 bird species are regularly sighted, including egrets, kingfishers, herons and raptors. Spelunkers flock to this nearly 10,000-hectare park, which features several...