Vypin is one of the group of islands that form part of the city of Kochi (Cochin), in the Indian state of Kerala. Vypin forms a barrier island which lies between the Arabian Sea in the west and the Cochin backwaters formed by the various distributaries of Periyar river, in the east. The northernmost end of the island lies on the estuary of the Periyar river in Muziris (Kodungallur), and the southernmost end in the mouth of the Cochin Backwaters in Kalamukku near Fort Vypin.

Barrier islands are a coastal landform, a type of dune system and sand island, where an area of sand has been formed by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything from a few islands to more than a dozen. They are subject to change during storms and other action, but absorb energy and protect the coastlines and create areas of protected waters where wetlands may flourish. A barrier chain may extend for hundreds of kilometers, with islands periodically separated by tidal inlets. The largest barrier island in the world is Padre Island of Texas, United States, at 113 miles (182 km) long. Sometimes an important inlet may close permanently, transforming an island into a peninsula, thus creating a barrier peninsula, often including a beach, barrier beach. Though many are long and narrow, the length and width of barriers and overall morphology of barrier coasts are related to parameters including tidal range, wave energy, sediment supply, sea-level trends, and basement controls. The amount of vegetation on the barrier has a large impact on the height and evolution of the island.