As you probably remember, the island of Phuket bore the brunt of a 2004 tsunami that swept hundreds of thousands of people to their deaths and ravaged Thailand and other island nations in the Indian Ocean. Thankfully, Thailand is on its way to recovery, due in part to a rebounding tourist trade, as more people discover the natural beauty that survived the devastation.
Phuket offers canoeists a system of interior caves and lagoons called hongs, the Thai word for rooms. Hongs were formed over millions of years. Undersea deposits of limestone, sand and clay were thrust upward due to shifts in the Earth's crust. Over time, wind and water eroded the softer minerals. In some places they ate through from the top down, creating open-aired channels. In others, they carved horizontally, leaving water-filled tunnels.
Paddling through the hongs is an awe-inspiring, and sometimes nerve-wracking, experience. Limestone stalactites hang down from some of the larger tunnels. Other tunnels look like little more than crevices, and you have to lie down in the canoe to avoid scraping your head on the sharp rock. The journey can be taken only at a certain point in the day (or night, for the bolder canoeist). At low tide, the waters are too shallow to float the canoe. At high tide, you risk being squeezed against a tunnel ceiling.