There is also this from wiki:

Marine sponges and their associated microbes produce an enormous array of antitumor, antiviral, anti-inflammatory, immunosuppressive, antibiotic and other bioactive molecules.[9][12][13] A total of 15 bacterial genera comprising 31 different bacterial species from the 9 collected marine sponges of the island. Among them Bacillus subtilis strains WS1A and YBS29 have great probiotic potential.[9][14][15] It can produce antimicrobial compounds and prevent motile Aeromonas septicemia disease (a major fish disease in Bangladesh) of Rohu (Labeo rohita).[9][14] Bacillus subtilis strains WS1A and YBS29 produce different types of antimicrobial peptides.[9][14][15] Fish (Labeo rohita) fed with extracellular products of Bacillus subtilis strains WS1A and YBS29 develop complete disease resistance.[9][14][15] The metabolites and bioactive compounds derived from marine sponges and sponge microbes also afford abundant potential for pharmaceutical and biotechnological applications.

So not only a desirable place for a base but also because of its offshore biodivesity, a bioweapons research lab with very few eyes on. This island was once part of the peninsula it lies south of but the land bridge is submerged. Its 3600 inhabitants make their living of fishing, rice and coconuts. They live in makeshift huts and there are few permanent buildings. There is a hospital but it often has no doctor. The weather in the Bay of Bengal makes this a dangerous place from October through April when an Indian Ocean tropical cyclone can devastate the island.