 Other evidence supporting this story are the fact that Richelieu was the first person to complete a hydrographic survey of the Andaman Sea including the area in question.The reef lies at in the Andaman Sea, about 80 km northwest of Khao Lak off Thailand's Phang Nga Province, very near to the provincial border of Ranong and about 18 km east of Surin island.There are no islands in the immediate vicinity of the reef.