An assessment by the Tamil Nadu Coastal Restoration Mission, Suganthi Devadason Marine Research Foundation and IIT Madras found a benefit-cost ratio of 2.34 for restoring Vaan Island. One of 21 uninhabited coral islands in the Gulf of Mannar, it shrank by 92% between 1969 and 2015 due to coral mining, reef damage and sea-level rise. Artificial reef modules placed from 2015 checked erosion, yielding socio-ecological benefits of ₹61.67 crore against a cost of ₹26.37 crore.