HTMS Sattakut

The Sattakut gives Koh Tao's graduates their first real wreck. Built in the United States as the landing craft infantry LCI-739 during the Second World War and later transferred to the Royal Thai Navy, she was cleaned and scuttled as an artificial reef in June 2011 and now sits upright on sand at about 30 m, her bow and stern guns still mounted and thoroughly photographed. The 48 m hull has settled into her role: schools of yellowtail barracuda and fusiliers over the deck, grouper in the companionways, porcupinefish loitering under the gun tubs. Prepared openings allow straightforward guided penetration for the trained; everyone else circuits the rails within comfortable Advanced limits.

The moment you come for: Mounted bow and stern guns, an intact upright hull at Advanced depth, easy first wreck penetrations

Topography: Steel hull upright on sand at about 30 m

Current: Generally manageable; occasional current across the deck calls for the line.

Entry: Scuttled near Hin Pee Wee off the west coast; buoy lines drop to the deck and dives often pair with the adjacent reef.

Hazards: Depth for the certification level it attracts, silt inside, and line traffic at peak times; penetrate only with training and lights.

Conservation: Purpose-sunk for divers and now functioning habitat; graffiti scratching and souvenir prying undo the point.

Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).