HTMS Sattakut: Koh Tao's Most Famous Wreck Dive Site

The HTMS Sattakut is the wreck every Koh Tao diver wants to tick off. This former landing craft served with the US Navy and then the Royal Thai Navy, and was sunk in June 2011 off the north-west of the island as an artificial reef. It lies on sand, with its superstructure rising to about 18 m and the stern reaching 30 to 32 m.

Among Koh Tao dive sites it is the best known wreck, and it is usually dived together with the pinnacles of Hin Pee Wee, a few metres to the north. The depth makes it a fun dive and an Advanced course site, rather than a first-week dive.

HTMS Sattakut dive site map

1. 2Sattakut hull, 18 to 32 m
2. 3Wheelhouse, top 18 m
3. 4Bow gun ~20 m
4. 5Stern gun, deep end
5. 6Hin Pee Wee pinnacles, top 8 m

Diving the HTMS Sattakut: the route

You descend the mooring toward the wheelhouse or the bow, then circle the wreck: bow gun, central corridor, stern gun. Then you leave the ship, swim north across the sand and finish by slowly coming up over the rocks of Hin Pee Wee. Doing the deep part first and the shallow part second is the standard plan, and it gives you more bottom time than a wreck-only dive.

Underwater layout

The ship is about 49 m long and 7 m wide. It has an open main deck, a two-level wheelhouse in the middle and a 40 mm anti-aircraft gun at each end. These guns are the classic photo spots.

• Bow: the gun sits at about 20 to 21 m. Entry points beneath its platform lead down stairs into the forward cabin.
• Wheelhouse: the shallowest point, at about 18 m. Three openings sit just below it, toward the bow.
• Corridor: a long central passage runs aft under the bridge, with rooms on either side that you can peer into through the portholes.
• Stern: a second gun covers the entrances to the corridor. This is the deepest end, at roughly 30 to 32 m depending on the tide. The bow is shallower, at around 26 m.

Accounts differ on whether the ship sits perfectly upright or leans slightly, so do not be surprised if it looks a little tilted.

Marine life at the Sattakut

Fish treat the wreck as home. Giant groupers, brown sweetlips and one-spot snapper hang around the hull and the superstructure, with yellowtail barracuda, butterflyfish and coral trout close by. Sea snakes and Jenkins whiprays pass through, and whale sharks have been reported nearby now and then.

Look closer for the small stuff: Durban dancing shrimp on the interior staircase, scorpionfish near doors and portholes, nudibranchs, and a skin of corals and sponges growing over the steel.

History of the wreck

She was launched on 27 February 1944 at the Commercial Ironworks in Portland, Oregon, as a US Navy Landing Craft Infantry (Large). A few years later she joined the Royal Thai Navy and was renamed HTMS Sattakut, after a Thai victory in the 1941 Franco-Thai War. After decades of patrol, training and transport work she was donated to Koh Tao by the Navy and the Department of Marine and Coastal Resources.

Crews stripped out hazardous materials, and the Navy sank her on 18 June 2011 in about 30 m of water, with support from local government and the dive industry. The idea was to create a new reef and take some pressure off the natural sites.

Conditions and best time to dive

Current is usually light to moderate. It picks up with the tide and is most noticeable on the exposed upper decks. Visibility is the big variable: anything from 5 to 20 m, with a typical day around 5 to 15 m and clearer days now and then. A thermocline often starts near 18 m.

The calmer months, roughly March to September, tend to be the best for west-coast sites. Visibility and surface conditions are often poorer from around November to January.

Tips from local divers

• Bring a torch, even for the lit sections. The inside is dark.
• Use nitrox or plan a multilevel profile: wreck first, then Hin Pee Wee.
• Keep your hands off the hull around doors and portholes, where scorpionfish hide.
• Pick a clear day for the guns if you want good photos.

Safety notes

At 30 m and more, narcosis and short no-decompression times are real. Open Water divers are limited to 18 m, which only reaches the top of the wheelhouse, so most centres run the Sattakut for Advanced or deep-qualified divers. Going inside the hull is an overhead environment and needs wreck specialty or technical training. Do not go beyond your training.

Why dive HTMS Sattakut

• Koh Tao's most famous wreck, sunk 18 June 2011
• Two 40 mm guns, bow and stern
• Open corridor, portholes and entry points
• Wheelhouse at about 18 m, hull down to 30 to 32 m
• Giant grouper, sweetlips and snapper
• Hin Pee Wee pinnacles next door for a shallow finish

HTMS Sattakut: frequently asked questions

Nearby dive sites

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