Green Rock

Green Rock lies off the northwest corner of Koh Nang Yuan and is a cluster of huge granite boulders that form a maze of swim-throughs, caverns, narrow passages and small caves. This topography is what divers come for, and it makes the site a favourite for navigation and buoyancy practice: the top of the main rock lies only about 2 m below the surface, and the site reaches about 28 to 30 m, including a small outlying pinnacle called Blue Rock at about 26 m. Just north of the boulders is an area divers call the 'trigger pits': titan and yellow-margin triggerfish breed there and defend their nests fiercely, especially in April and May. Schools of yellowtail barracuda hang over the rocks, the cracks hold nudibranchs, shrimps, pipefish and scorpionfish, and turtles, blue-spotted stingrays and occasionally whale sharks visit. Because the site is exposed to the open sea beyond Koh Nang Yuan, current and visibility can vary, so the deeper parts and tighter passages suit Advanced divers, while Open Water divers can enjoy the upper sections in good conditions.