Between November and April, the deep ocean off Mirissa hosts the Indian Ocean’s largest seasonal blue whale aggregation, animals up to 30 metres long surfacing within close range of small boats in a way that never becomes ordinary. Spinner dolphin pods of several hundred individuals frequently accompany the return journey. Venture Ceylon arranges whale watching with responsible operators who prioritise animal welfare, and briefs guests on marine behaviour so the encounter is understood as well as witnessed. Seasonal whale watching also runs from Trincomalee between May and October.