Southwest Pinnacle

Koh Tao · Surat Thani · Thailand

Southwest Pinnacle stands as Koh Tao's premier deep dive site, a collection of granite boulders rising from the sandy bottom at 26 metres to within 6 metres of the surface. Located roughly two kilometres southwest of the island, this submerged mountain attracts some of the Gulf of Thailand's most impressive marine life, from seasonal bull shark appearances to resident schools of giant trevally numbering in the hundreds. The site consists of a main pinnacle surrounded by several smaller rock formations, creating a complex underwater landscape of swim-throughs, overhangs, and vertical walls. Every surface is carpeted in soft corals ranging from pale pink to vivid orange, interspersed with massive barrel sponges that can exceed a metre in diameter. The granite boulders are stacked in stepped formations, allowing divers to gradually ascend while exploring different habitats at each depth level. Below 20 metres, the deeper boulders host large groupers tucked into crevices and blue-spotted stingrays resting on the sand patches between rocks. Schools of yellow-banded fusiliers form shimmering curtains around the pinnacle, attracting predators like chevron barracuda and giant trevally. Between December and March, lucky divers may encounter bull sharks patrolling the deeper sections, making this one of the few sites in the Gulf where shark encounters remain possible. The summit area between 6 and 12 metres provides an excellent safety stop zone with dense coral coverage and clouds of damselfish. Anemones hosting families of clownfish dot the upper rocks, while hawksbill turtles occasionally visit to feed on sponges. Visibility ranges widely from 10 metres during plankton blooms to exceptional 30 metre days during the calm season. Morning dives typically offer the best conditions before afternoon winds stir the surface.