Coral reefs of Sri Lanka

Sri Lanka's reefs fall into three broad groups. Fringing coral reefs sit close to shore on the south-west and east coasts, at places like Hikkaduwa, Rumassala, Unawatuna, Polhena and Pigeon Island. The Bar Reef system off Kalpitiya in the north-west is the largest, a semi-barrier structure covering a substantial area. And there are sandstone and rock reefs, most famously the Great and Little Basses off the deep south, which are dramatic dive sites rather than snorkelling spots.

Because the reefs sit on opposite coasts, their seasons are opposite too. East coast reefs are calm and clear from roughly May to September. South-west coast reefs are calm and clear from roughly November to April. There is no month when all of them are good at once.

Pigeon Island National Park, a short boat ride off Nilaveli on the east coast, is the reef most visitors should aim for. The shallow lagoon on the island's sheltered side has living coral within a few metres of the sand, along with parrotfish, angelfish, surgeonfish and, reliably, blacktip reef sharks patrolling the shallows. They are small, harmless to people, and one of the most memorable things you will see with a mask on in Sri Lanka.

It is a protected national park with an entry fee, boat regulations and daily visitor limits, which help but do not eliminate pressure. The island gets busy from mid-morning. Take the earliest boat, stay off the coral, and consider the outer edge of the lagoon where there is more space and better structure.

The Bar Reef Marine Sanctuary off Kalpitiya is Sri Lanka's largest reef complex and, in good conditions, offers the best visibility in the country. It supports high fish diversity and is reached by boat from the Kalpitiya peninsula in the calm season, roughly December to April.

Bar Reef suffered severely in the 1998 bleaching event, with reports of very high coral mortality across parts of the system, and again during the 2016 event. Recovery has been patchy. It is still a worthwhile dive and snorkel, particularly for fish life, but anyone expecting an intact Indian Ocean barrier reef will be disappointed.

Hikkaduwa Marine National Park is the most accessible reef on this coast, snorkellable straight off the beach without a boat, which is genuinely rare. Coral cover has declined substantially over the decades from bleaching, storm damage and visitor pressure, but fish life remains good and turtles are common.

Rumassala, the headland between Unawatuna and Jungle Beach, has rocky reef in sheltered water that suits nervous snorkellers. Polhena near Matara has a shallow reef-protected lagoon where turtles feed. None of these are spectacular reefs, but all are easy, safe and warm, and they are what the south-west coast has.

Sri Lanka's reefs have had a hard time. The 1998 El Nino bleaching event caused mass coral mortality across the Indian Ocean and hit Sri Lankan reefs particularly hard, with Bar Reef and Hikkaduwa among the worst affected. The 2004 tsunami caused physical damage in places. A further global bleaching event in 2016 set back much of the recovery that had occurred.

Layered on top are local pressures: destructive fishing practices in some areas, sedimentation from coastal development and river discharge, anchor damage, and simple visitor contact. The reefs that have done best are those with genuine protection and enforcement, which is the argument for paying the national park fees rather than resenting them.

None of this means you should not go. Reef tourism, done properly, is one of the strongest arguments a community has for protecting a reef. It means you should go with realistic expectations and behave well when you get there.

The single most damaging thing visitors do is stand on coral. In shallow lagoons like Pigeon Island the temptation is constant, and a moment of resting a foot down can break growth that took years. Wear fins, float, and if you need to rest, move to sand.

Sunscreen matters too. Oxybenzone and octinoxate, common in chemical sunscreens, are associated with coral harm. A long-sleeved rash vest is the most effective answer because it removes the need for sunscreen on your back and shoulders entirely; where you do need it, choose a mineral formulation based on non-nano zinc oxide.

If reefs matter to you, let them choose your dates. A May to September trip built around Nilaveli and Pigeon Island will give you far better snorkelling than a November to April trip built around the south-west, where the reefs are convenient rather than impressive.

Lankan Stays & Trails arranges Pigeon Island trips on the first boat of the morning and works with operators who brief properly and enforce no-contact rules. We would rather send you at dawn with a good guide than at eleven with a crowd.