
Sail Rock
Overview
Sail Rock (Hin Bai) is the Gulf of Thailand's most celebrated dive site, a massive underwater granite pinnacle rising from the seabed at 30+ meters to about 15 meters above the surface. Located between Koh Phangan and Koh Tao, it stands alone in open water, acting as a magnet for marine life. The rock's signature feature is the Chimney — a vertical swim-through passage that pierces the rock, allowing divers to enter at around 18 meters and exit at approximately 6 meters, or vice versa. Swimming up through the Chimney as light floods in from above is one of the most memorable experiences in Gulf of Thailand diving. The rock's surface is covered in anemones, barrel sponges, and hard corals, supporting dense communities of butterflyfish, angelfish, and anemonefish. Massive schools of batfish orbit the rock, and barracuda hold formation in the blue. Large groupers and trevally patrol the deeper sections. Sail Rock is the Gulf's most reliable location for whale shark encounters — these gentle giants visit during their seasonal migration, with sightings peaking between March and June. Nudibranchs and seahorses reward macro photographers on every dive. The site is reached by boat from Koh Tao (90 minutes), Koh Phangan (60 minutes), or Koh Samui (90 minutes). Conditions can vary significantly — visibility ranges from 10 to 30 meters, and currents can be strong around the rock.
Marine life
Dive profile
DEPTH PROFILE
DEPTH PROGRESSION & WAYPOINTS: Sail Rock
Location
Near Koh Phangan, in the Gulf of Thailand region of Thailand.
Frequently asked questions
What certification is needed for Sail Rock?
Advanced Open Water certification is recommended. The rock drops to 30+ meters, and the famous Chimney swim-through requires comfort with vertical descents. Open Water divers can enjoy the shallower sections with a guide.
When is the best time to dive Sail Rock?
March to October offers the best conditions in the Gulf of Thailand. Whale shark season peaks around March to June, though sightings can occur through October. Visibility ranges from 10 to 30 meters.
What is the Chimney at Sail Rock?
The Chimney is a vertical swim-through — an opening in the rock at about 18 meters that you can enter from the top or bottom. It's roughly 5 meters tall and wide enough for one diver, creating an exciting passage through the rock formation.
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Data Provenance
This profile is compiled from 3 operator submissions and 142 community logs. Key facts (depth, entry) are verified against official hydrographic charts.