Snorkelling and Diving in Sri Lanka: The Sites and the Seasons

Hawksbill Turtle Regular Critically Endangered

Eretmochelys imbricata

The reef's sponge specialist, its beautiful shell also the reason it was hunted to the edge.

Where: Reef at Pigeon Island and off Nilaveli. Best: May to September. The single best place in Sri Lanka to see one.

Green Sea Turtle Regular

Chelonia mydas

The great grazing turtle of the tropics, the only sea turtle that turns vegetarian as an adult.

Where: Shallow reef and seagrass at Pigeon Island and Nilaveli. Best: May to September.

Loggerhead Turtle Rare Vulnerable

Caretta caretta

Jaws powerful enough to crush a queen conch, and it navigates ocean basins by reading the earth's magnetic field.

Where: Coastal water and reef edges, usually juveniles. Best: May to September.

Whale Shark Rare Endangered

Rhincodon typus

The biggest fish in the ocean, a spotted, bus sized filter feeder and the undisputed holy grail of tropical diving.

Where: Blue water beyond the reef. Best: May to September.

Blacktip Reef Shark Common Vulnerable

Carcharhinus melanopterus

The neat little reef shark of the shallows, its black-tipped fins often cutting the surface over sun-lit sand flats.

Where: The shallow inner reef at Pigeon Island, in snorkelling depth. Best: May to September. The single most reliable place in Sri Lanka to see a shark, and you do not need to dive. Dozens patrol water barely over head height.

Powder Blue Surgeonfish Common

Acanthurus leucosternon

A stunning Andaman signature fish, powder blue with a yellow sail and a scalpel-sharp blade at the base of its tail.

Where: Shoaling over the reef top at Pigeon Island. Best: May to September. They graze in loose shoals that pour over the coral like a blue tide.

Reef Manta Ray Rare Vulnerable

Mobula alfredi

A four metre wingspan gliding overhead in slow, hypnotic loops that leave divers grinning for days.

Where: Deeper reef edges and cleaning stations. Best: May to September.

Staghorn Coral Common

Acropora species

The fast-growing branching coral that builds the living thickets of the reef, nursery and shelter for a whole community.

Where: The shallow reef flat inside the island. Best: May to September. Badly hit by bleaching in 2016 and recovering unevenly, and it breaks under a fin or a foot.

Black Pyramid Butterflyfish Regular

Hemitaurichthys zoster

They gather in the current in hundreds, and the white wedge on each flank turns the whole shoal into a drifting cloud of triangles.

Where: The drop-off edges off Pigeon Island and the Trincomalee canyon rim. Best: May to September.

Indian Sailfin Tang Regular

Zebrasoma desjardinii

It raises a dorsal fin nearly as tall as its own body, and a startled one seems to double in size in front of you.

Where: Reef top and boulder slopes at Pigeon Island. Best: May to September.

Maldives Anemonefish Regular

Amphiprion nigripes

A clownfish found only in Sri Lanka, the Maldives and the Lakshadweep, and nowhere else on earth.

Where: Anemones on the inner reef at Pigeon Island and off Nilaveli. Best: May to September.

Sebae Anemonefish Regular

Amphiprion sebae

The big dark anemonefish of the northern Indian Ocean, with a yellow tail that gives it away from a distance.

Where: Sand and rubble margins off Nilaveli and Pigeon Island. Best: May to September.

Titan Triggerfish Regular

Balistoides viridescens

The reef's bad tempered bulldozer, a heavy triggerfish that bites chunks out of coral to get at what is living underneath it.

Where: Reef flat and slope, nesting in the sand patches. Best: May to September. Nests on the sand between coral heads on the shallower sites.

Yellowhead Butterflyfish Regular

Chaetodon xanthocephalus

An Indian Ocean butterflyfish that pairs for life, and you almost never see one without the other close by.

Where: Sheltered coral at Pigeon Island and Nilaveli. Best: May to September.

Green Sea Turtle Common

Chelonia mydas

The great grazing turtle of the tropics, the only sea turtle that turns vegetarian as an adult.

Where: The shallow reef and the beach shallows, where turtles come in to be fed by hotels. Best: November to April. Turtles here are habituated and hand fed, which is why they are so easy to see. That is a fed animal, not a wild encounter, and it is worth knowing the difference.

Hawksbill Turtle Occasional Critically Endangered

Eretmochelys imbricata

The reef's sponge specialist, its beautiful shell also the reason it was hunted to the edge.

Where: Coral on the fringing reef. Best: November to April.

Olive Ridley Turtle Occasional Vulnerable

Lepidochelys olivacea

The smallest and most numerous sea turtle, famous elsewhere for mass nestings of thousands at once.

Where: Offshore water and occasionally over the reef. Best: Year round.

Bluestreak Cleaner Wrasse Regular

Labroides dimidiatus

A tiny striped wrasse that runs the reef's health clinic, picking parasites from fish that queue up and even open their mouths for it.

Where: Cleaning stations on the larger coral heads. Best: November to April.

Moorish Idol Regular

Zanclus cornutus

An unmistakable disc of black, white and gold trailing a long ribbon fin, one of the most elegant fish on any reef.

Where: Fringing reef and rocky patches. Best: November to April.

Blacktip Reef Shark Rare Vulnerable

Carcharhinus melanopterus

The neat little reef shark of the shallows, its black-tipped fins often cutting the surface over sun-lit sand flats.

Where: The outer reef edge rather than the shallow flat. Best: November to April.

Bluespotted Ribbontail Ray Occasional

Taeniura lymma

A small, brilliantly marked ray, olive gold studded with electric blue spots, tucked under coral ledges.

Where: Sand patches and under ledges at the reef edge. Best: November to April.

Magnificent Sea Anemone Occasional

Heteractis magnifica

A great carpet of stinging tentacles that is home and fortress to the anemonefish, a partnership at the heart of the reef.

Where: Coral heads on the reef flat, hosting the anemonefish. Best: Year round.

Table Coral Occasional Near Threatened

Acropora hyacinthus

Grows outward faster than it grows up, spreading a flat platform that shades out every competitor beneath it.

Where: The shallow reef flat inside the marine park. Best: Year round.

Blue-green Chromis Common

Chromis viridis

A shimmer of living jewels above the coral, hundreds of tiny blue-green fish that vanish into the branches in a blink.

Where: Above coral heads on the fringing reef. Best: November to April.

Green Sea Turtle Regular

Chelonia mydas

The great grazing turtle of the tropics, the only sea turtle that turns vegetarian as an adult.

Where: Bar Reef and the surrounding shallows. Best: November to April.

Hawksbill Turtle Occasional Critically Endangered

Eretmochelys imbricata

The reef's sponge specialist, its beautiful shell also the reason it was hunted to the edge.

Where: Bar Reef Marine Sanctuary. Best: November to April.

Blacktip Reef Shark Occasional Vulnerable

Carcharhinus melanopterus

The neat little reef shark of the shallows, its black-tipped fins often cutting the surface over sun-lit sand flats.

Where: Shallow reef and sand flats around Bar Reef. Best: November to April.

Olive Ridley Turtle Occasional Vulnerable

Lepidochelys olivacea

The smallest and most numerous sea turtle, famous elsewhere for mass nestings of thousands at once.

Where: Nesting beaches around Kandakuliya, and offshore. Best: November to March. Sri Lankan waters feed animals that nest at the Odisha arribadas in India.

Powder Blue Surgeonfish Common

Acanthurus leucosternon

A stunning Andaman signature fish, powder blue with a yellow sail and a scalpel-sharp blade at the base of its tail.

Where: Grazing the coral tops of Bar Reef. Best: November to April.

Staghorn Coral Common

Acropora species

The fast-growing branching coral that builds the living thickets of the reef, nursery and shelter for a whole community.

Where: Bar Reef, the largest reef system in Sri Lanka. Best: November to April. Bar Reef was severely bleached in 1998 and again in 2016. What is there now is regrowth.

Maldives Anemonefish Regular

Amphiprion nigripes

A clownfish found only in Sri Lanka, the Maldives and the Lakshadweep, and nowhere else on earth.

Where: Anemones on the shallow coral of Bar Reef. Best: November to April.

Sebae Anemonefish Regular

Amphiprion sebae

The big dark anemonefish of the northern Indian Ocean, with a yellow tail that gives it away from a distance.

Where: Sandy margins and carpet anemones around Bar Reef. Best: November to April.

Table Coral Regular Near Threatened

Acropora hyacinthus

Grows outward faster than it grows up, spreading a flat platform that shades out every competitor beneath it.

Where: Bar Reef coral flats. Best: November to April.

Small Giant Clam Regular

Tridacna maxima

The electric blue and green lips are not pigment for show. They are farming light, and the clam gets most of its food from algae living in its own flesh.

Where: Shallow coral of Bar Reef. Best: November to April.

Black Pyramid Butterflyfish Occasional

Hemitaurichthys zoster

They gather in the current in hundreds, and the white wedge on each flank turns the whole shoal into a drifting cloud of triangles.

Where: Current-swept edges of Bar Reef. Best: November to April.

Indian Sailfin Tang Occasional

Zebrasoma desjardinii

It raises a dorsal fin nearly as tall as its own body, and a startled one seems to double in size in front of you.

Where: Bar Reef coral tops. Best: November to April.

Hawksbill Turtle Occasional Critically Endangered

Eretmochelys imbricata

The reef's sponge specialist, its beautiful shell also the reason it was hunted to the edge.

Where: The reef structure and its overhangs. Best: March to April.

Green Sea Turtle Occasional

Chelonia mydas

The great grazing turtle of the tropics, the only sea turtle that turns vegetarian as an adult.

Where: Resting on ledges and feeding on the reef. Best: March to April.

Whale Shark Rare Endangered

Rhincodon typus

The biggest fish in the ocean, a spotted, bus sized filter feeder and the undisputed holy grail of tropical diving.

Where: Open water at the reef. Best: March to April. Records cluster around the Basses in the short diving season.

Humphead Wrasse (Napoleon Wrasse) Rare Endangered

Cheilinus undulatus

A giant, curious reef fish with thick lips and a bulging forehead, able to crunch prey that few other animals can eat.

Where: Deeper reef and gullies. Best: March to April.

Giant Trevally Regular

Caranx ignobilis

A silver battering ram that hunts by simply outrunning everything, and has been filmed taking birds off the surface.

Where: Hunting in the current over the reef. Best: March to April. Trevally hunt the reef edge here in numbers that do not happen on the sheltered coasts.

Giant Grouper Occasional

Epinephelus lanceolatus

The giant of the reef, a grouper that can grow larger than a diver and swallow prey the size of a small shark.

Where: Ledges and gullies on the Great Basses reef. Best: March to April. The Basses hold the biggest reef fish in Sri Lankan water, because the conditions keep the fishing pressure off.

Grey Reef Shark Occasional Endangered

Carcharhinus amblyrhynchos

The classic requiem shark of the drop-off, bold and inquisitive where currents sweep the reef.

Where: The reef edge and drop-offs. Best: March to April.

Emperor Angelfish Occasional

Pomacanthus imperator

A living work of art in electric blue and yellow stripes, its young disguised in a maze of blue and white rings.

Where: Ledges and swim-throughs in the reef structure. Best: March to April.

Giant Sea Fan (Gorgonian) Regular

Annella species

A great lattice fan spread across the current, a soft coral that farms the flow for plankton and shelters seahorses and hawkfish.

Where: Current swept reef faces. Best: March to April.

Black Coral Occasional

Antipathes dichotoma

Colonies have been aged at over four thousand years, making them among the oldest living animals on the planet.

Where: Deeper gullies and overhangs. Best: March to April.