Samae San Island (, , ) is a small island in Sattahip District, Chonburi Province of Thailand.
Samae San Island has a length of four kilometres and its maximum width is about one kilometre. The island is thickly wooded and uninhabited. Formerly there was a fishing village on Samae San Island, but it was vacated and the island now is under the control of the Royal Thai Navy. Some 1,240 families reside in the fishing village of Ban Samae San on the mainland. Administratively the islands belong to the Samae San Sub-district of Sattahip.
There are four main islands in the Samae San group. The northern cluster surrounds Samae San Island, while the southern subgroup is centered on Ko Chuang. Chuang Island has a small bay at its southern end. Hin Chalam (Shark Rock) is five kilometres to the south of the southern end of the group.
The Ko Kham Undersea Park is part of a royal project of Princess Maha Chakri Sirindhorn that preserves the plants and animals of the sea and island. It is home to many kinds of fish, including bluespotted stingrays, moray eels, fusilier fish, angel fish and lionfish.
Visitors are restricted, although tourist attractions on the island include fishing, swimming, bicycle riding and hiking. The islands are also well known for their diving areas. The area is particularly renowned for its technical diving with a number of local sites featuring on the list of deepest dive sites in the Gulf of Thailand, with the deepest being the Samaesan Hole. The Samaesan Hole is considered on of the most extreme dive sites in the world due to a number of hazards including: depth, poor visibility, darkness, unexploded ordinance, strong and unpredictable currents as well as it being situated in a commercial shipping lane. Since the island is within a military area, off-limits for casual tourists, booking has to be done through local travel agents.