Kalmunai

In the same Easter Sunday raid of 1942 that sank the H.M.S. Hermes off Batticaloa, Japanese carrier aircraft pressed further south and sank the British oil tanker SS Athelstane and the Flower-class corvette HMS Hollyhock. Both are believed to now lie around 42 metres off the coast of South Kalmunai.

Unlike its better-known neighbours, Kalmunai has no established dive centres — diving here is still expedition-style, requiring special arrangement, and much of the region's wreck and reef inventory is still being surveyed and documented rather than routinely dived.

The season runs May to October. For technical and wreck-focused divers looking to go beyond Sri Lanka's more established sites, Kalmunai offers a genuine frontier: confirmed WWII history, a scatter of further wrecks and reefs, and very few other divers.