Grey Reef Shark
Scientific name Carcharhinus amblyrhynchos
The Grey Reef Shark is a sleek, powerful reef predator and one of the most iconic shark species of the Indo-Pacific. Recognisable by its streamlined grey body, white underside and distinctive black edging on the tail fin, it is built for speed and agility.
Growing up to around 2 metres in length, Grey Reef Sharks are typically seen patrolling reef drop-offs and offshore pinnacles. Around Koh Tao, sightings are occasional but more likely at deeper, current-exposed sites between 15–35 metres.
They are active daytime hunters and often cruise just off the reef edge in blue water. In areas with strong current, they may be seen swimming steadily into the flow, conserving energy while scanning for prey.
Grey Reef Sharks are curious but cautious around divers. Calm behaviour and good buoyancy are key to respectful encounters. In rare cases, they may display territorial behaviour such as exaggerated swimming patterns, which is simply a sign to give them more space.
As apex predators, they play a critical role in maintaining reef ecosystem balance by regulating populations of mid-level fish species.
Find Grey Reef Shark at...
Divemaster's tip
Spend time looking into the blue beyond the reef edge rather than focusing only on coral. Sharks often patrol slightly off the main structure.
Remain calm, stay vertical and avoid sudden movements. If one approaches, maintain eye contact without chasing or blocking its path.
What do they eat?
Grey Reef Sharks feed primarily on reef fish, squid and crustaceans.
Their speed, sharp senses and coordinated hunting ability make them one of the top predators in Koh Tao’s offshore reef ecosystems.
