Eastern Province

Sri Lanka's Eastern Province faces the Bay of Bengal from Trincomalee in the north to Pottuvil and Arugam Bay near the southern end of the coast. The tidal pattern is mixed semidiurnal; spring range at Trincomalee runs approximately 0.8 to 1.1 metres above chart datum, modestly smaller than the western-coast range at Colombo and significantly smaller than the ranges in the northern Bay of Bengal. NARA (National Aquatic Resources Research and Development Agency, Sri Lanka) operates the authoritative coastal tide gauge network for Sri Lanka. The defining seasonal character of this coast is its inverse relationship to Sri Lanka's western and southern shores: the SW monsoon (May to September) that brings rough seas and rain to Colombo, Galle, and the west coast drives swell around Sri Lanka's southern tip and into the eastern bay, delivering the surf that makes Arugam Bay one of Asia's best-known point breaks. The east coast becomes calm and swimmable from October when the monsoon retreats. The Bay of Bengal climate influence is also relevant: the northeast monsoon (October to January) can bring significant weather from the northeast, with both wave height and rainfall elevated. Trincomalee Harbour, one of the world's largest natural deep-water harbours at roughly 5 km wide and 10 km deep, is calm year-round because three of its four sides are sheltered by land; it was used as a Royal Navy fleet anchorage in both World Wars. The eastern-coast beaches — Nilaveli, Marble Beach, Uppuveli, Pasikudah — benefit from the clear blue Bay of Bengal water in the calm season and from the coral reefs and wrecks accessible offshore.