HTMS Sattakut

The Sattakut had two careers separated by an ocean. Launched in 1944 as a US Navy landing craft infantry — one of the flat-bottomed troop carriers built by the hundred for the island war — she saw Pacific service before being transferred to the Royal Thai Navy in the late 1940s, which kept her working as a patrol vessel for decades under the name Sattakut. When her service finally ended, the navy donated the hull, and on 18 June 2011 she was cleaned and scuttled a short boat ride from Koh Tao's western shore, near the pinnacle of Hin Pee Wee. She sits upright on the sand, bow gun still mounted and pointing into the green, wheelhouse doorways cut wide for safe swim-throughs. On an island that certifies more new divers than almost anywhere on earth, she has become the standard first wreck: deep enough to matter, small enough to circle twice, and reliably escorted by batfish.

How she sank: Decommissioned and deliberately scuttled off Koh Tao on 18 June 2011 as an artificial reef.

Condition: Young, tidy, and intact, with sponge and oyster growth accelerating each season.

Penetration: Limited. Prepared openings allow supervised passes through the wheelhouse and deck spaces; the lower hull silts and is left to wreck courses. Entering any overhead environment requires specific training — a wreck certification at minimum, technical wreck training for full penetration.

Recommended certification: Advanced Open Water

Current: Mild · Visibility: 5–20 m

Marine life: Batfish escort divers on the line, snapper and fusiliers stream over the gun, porcupinefish loiter in the wheelhouse, and groupers hold the shadow under the stern.

Hazards: Visibility swings widely with season; multiple training groups can crowd the mooring; mind gas at a site deeper than the island's reefs.

An artificial reef stays complete only if every diver leaves it so.