Unveiling Chennai's Marine Marvels

Diving at Depth

- Abhinav Sitaraman

Beneath the rough, choppy, tumultuous waves of the Bay of Bengal, a kaleidoscope of marine life thrives just 8–12 km off Chennai’s Neelankarai coast. In this column, Abhinav Sitaraman invites you to explore a world of vibrant colours and extraordinary creatures, captured during 11 dives between January 2021 and March 2023. From the sunlit shallows at 12–18 meters to thriving natural and artificial reefs, these underwater ecosystems are teeming with life—each species a testament to the ocean’s boundless creativity and resilience.

Chromodoris geminus: It is closely related to terrestrial snails and slugs, collectively known as gastropods. These colourful sea-slugs are called nudibranchs, coming from the Latin nudus; ‘naked’ and the Ancient Greek bránchia; ‘gills’. The white hair-like structures on the left-hand side are the gills through which they breathe, and the two yellow rice grain-like structures on the right-hand side are the sensory organs through which they find food, communicate, and sense changes in water pressure and vibrations. Nudibranchs have evolved with distinct and vibrant colours to let potential predators know they are poisonous if consumed. First observed at a dive site named ‘Big Rock’, where large underwater rock structures create dense habitats. Such rock structures are spread across the southern Coromandel Coast, also providing important fishing grounds for traditional fishermen.