Sri Lanka's east-coast dive hub, where Pigeon Island Marine National Park shelters one of the country's best-preserved coral reefs and a year-round blacktip reef shark aggregation, and the deep WWII wreck of HMS Hermes lies offshore for technical divers.
Destination info
Conditions, highlights, and the resident marine life.
Conditions
Water and air temperature across the year.
WaterAirDryShoulderWet
Description
Trincomalee, with the resort village of Nilaveli, is Sri Lanka's premier east-coast diving base. Its season runs roughly May–September, the inverse of the west and south coasts, because the southwest monsoon flattens this side of the island while battering the others. The headline site is Pigeon Island Marine National Park, a 471-hectare protected reef 1 km off Nilaveli (sanctuary 1963, national park 2003) holding around 100 coral species and 300 reef-fish species, three sea-turtle species, and the only regular blacktip reef shark (Carcharhinus melanopterus) aggregation on Sri Lanka's east coast—though the sharks are typically seen by snorkellers in the shallow lagoon rather than on scuba. Most diving is gentle reef and rock work at 5–20 m: Swami Rock beneath Trincomalee's clifftop Hindu temple, coral gardens, pinnacles, and a cluster of WWII and modern wrecks. The famous prize is HMS Hermes, the world's first purpose-built aircraft carrier, sunk by Japanese aircraft on 9 April 1942 and now lying on her side at roughly 50–55 m off Batticaloa to the south—an advanced technical dive requiring TEC/trimix certification. Divers should know that Pigeon Island's reefs suffered severe bleaching in 2016 with slow recovery, so coral condition varies by site.
Highlights
What makes this dive worth the trip.
Pigeon Island holds the only known regular aggregation of blacktip reef sharks (Carcharhinus melanopterus) on Sri Lanka's east coast—designated an Important Shark and Ray Area (ISRA). Groups of 2–10 (occasionally up to 30) were recorded on all 10 research trips across the calm season (May–October) 2017–2023, with near-daily sightings reported by park wardens; the species is IUCN Vulnerable.
Trincomalee's diving season (roughly May–September) is the mirror image of Sri Lanka's west and south coasts: the southwest monsoon that closes Hikkaduwa and the south leaves the east coast calm, clear and diveable, with visibility commonly 15–30 m.
HMS Hermes—the world's first ship designed and built as an aircraft carrier—was sunk by Japanese dive-bombers on 9 April 1942 with the loss of 307 men, and now rests on her port side at roughly 50–55 m off Batticaloa. It is a serious technical dive: TEC deep / trimix certification is required, and operators run it as a dedicated expedition rather than a recreational outing.
Marine life
35 species you’re likely to encounter on a dive here.
Dive sites
8 signature sites at this destination.
Pigeon Island North Reef
A shallow hard-coral reef in the protected Pigeon Island Marine National Park, often cited as one of the best sites in the area for beginners. Extensive coral beds dotted with Christmas-tree tube worms, anemones with clownfish, and dense schools of reef fish. The park's blacktip reef sharks patrol the surrounding shallows, though they are usually encountered by snorkellers in the lagoon rather than by divers. Calm, shallow and easily accessed by short boat ride from Nilaveli.
5–18 mbeginnerDay boatLightVisibility 15–30 m
Swami Rock
A submerged rock landscape directly below Trincomalee's clifftop Koneswaram Hindu temple on Swami Rock headland, combining diving with cultural setting. Boulders and ledges run from about 10 m down to 35 m, drawing groupers, stingrays, schooling reef fish, and the occasional larger pelagic or reef shark on the deeper sections. Underwater statues of Hindu deities have been placed at the site. Depth and topography make the deeper portion intermediate-to-advanced.
10–35 mintermediateDay boatModerateVisibility 10–25 m
Irakkandy Wreck (SS Ava)
A 19th-century iron steamer (reported lost in 1858) lying shallow at roughly 6–11 m, now completely encrusted in corals, anemones and sponges so it functions as a thriving artificial reef. Nudibranchs, molluscs, moray eels and clouds of reef fish populate the structure, with occasional pelagics passing by. The shallow depth makes it an easy, atmospheric wreck dive accessible to all levels.
6–11 mbeginnerDay boatLightVisibility 8–20 m
Gunboat Wrecks (Weeraya P311 & Jagatha P315)
Two decommissioned Sri Lanka Navy gunboats deliberately scuttled in 2020 as artificial reefs, lying roughly 10–20 m apart at 14–17 m. Still relatively intact, the hulls are colonising with marine growth and already attract schooling fish, with the pair often dived together. A straightforward intermediate wreck dive that gives recreational divers a wreck experience without the depth or certification demands of HMS Hermes.
14–17 mintermediateDay boatLightVisibility 10–25 m
SS British Sergeant Wreck
A WWII British tanker sunk off the Sri Lankan east coast on 9 April 1942 during the Japanese Indian Ocean raid, now broken into two main sections on a sandy bottom at around 24 m. Large holes and caverns in the hull shelter schools of fish and can be swum through, making it an engaging intermediate-to-advanced recreational wreck dive—deeper and more demanding than the shallow Irakkandy and gunboat wrecks but well within recreational limits, unlike Hermes.
18–28 madvancedDay boatModerateVisibility 10–25 m
HMS Hermes (technical)
The wreck of the world's first purpose-built aircraft carrier, sunk by Japanese aircraft on 9 April 1942 with the loss of 307 men, lying on her port side off Batticaloa to the south of Trincomalee. The 182 m hull is heavily collapsed but draped in black-coral trees and gorgonians, with guns, a rangefinder and other artefacts among the remains. At roughly 50–55 m this is a serious technical dive—TEC deep / trimix training is required and operators run it as a dedicated expedition, not a recreational outing. Often staged from Trincomalee or Batticaloa in the May–September window.
42–55 madvancedDay boatStrongVisibility 15–40 m
Coral Bay (Coral Bay Rock)
A shallow, picturesque site about 20 minutes by boat, with a maximum depth around 13 m over hard- and soft-coral gardens. A relaxed, beginner-friendly dive rich in reef fish—barracuda, pufferfish, triggerfish, lionfish—plus well-camouflaged stonefish and the occasional turtle. Good visibility and gentle conditions make it a common second or check dive.
5–13 mbeginnerDay boatLightVisibility 10–25 m
Pigeon Island East Rocks
Scenic granite rock formations on the seaward side of Pigeon Island, dropping from about 7 to 18 m. Boulders and swim-throughs shelter schools of fusiliers and snappers, moray eels in the crevices, and rays cruising the sand patches between rocks. A step up in depth and interest from the shallow North Reef, suitable for divers with basic open-water experience.
7–18 mbeginnerDay boatLightVisibility 15–30 m
Where to dive & stay
Local dive centers, resorts, and hotels.
Featured operators coming soon
Verified dive centers, resorts, and hotels around Trincomalee / Pigeon Island will list here — pricing, photos, and direct contact.
