Surrounded by the warm waters of the Indian Ocean, Sri Lanka offers exceptional diving opportunities along its southern and western shores. Reliable dive-tour packages and underwater safaris and expeditions are offered by specialist agencies. Shipwreck dives are of special interest.
You can find good diving all around Sri Lanka except off the north coast. The island essentially sits atop a huge sandbank that drops 3000m into deep ocean. This drop-off is anything from 1km to 10km offshore. Close in you usually find shallow sand or rock bottoms, but in places, especially along the east coast and wild south coast, you can also dive on walls and drop-offs. Because you're seldom far from deep water, opportunities for encounters with pelagics, sharks and other inhabitants of the open ocean abound. Adrenalin levels are highest in the east - at places like Trincomalee - and in the south, at the wonderful Basses Reefs, arguably the most adventurous diving in the country.
Wrecks are a particular attraction of Sri Lankan diving. The island has long been on international trade routes - including the spice and tea runs between Europe and East Asia - and over the centuries its treacherous coastline has claimed many ships. Among the best-known are the SS Conch, the world's first oil tanker, near Hikkaduwa; and the British aircraft carrier HMS Hermes, sunk off the east coast during World War II. Many of the wrecks you'll dive on have virtually disintegrated, partially as a result of their age, the natural action of the sea or persistent salvage attempts by local divers. But the remaining hull fragments are often still interesting to divers for the abundant marine life they attract. The sea off Colombo has a particularly high concentration of wrecks.
Sri Lankan diving is split into two basic seasons: one for the east coast and one for the west. You dive on the side of the island that's not directly exposed to the prevailing monsoon. For example, from late November to early March, when the northeast monsoon is blowing, diving conditions are best on the west coast. Conversely, from March to September, during the southwest monsoon, the east coast has calm seas. The further south you go on either coast, the shorter the season.
Pigeon Island off Nilaveli (north of Trincomalee) is a fine place to go snorkeling.
You also can snorkel at Hikkaduwa, Unawatuna, Mirissa and at Polhena near Matara.
Diving shops can be found in Colombo and in the major West Coast resorts.
They hire and sell all types of diving gear, including snorkeling equipment.
PADI courses are available, as well as lessons for beginners and dives for more experienced people.