Actually looking at a map, the island is a mere 20km from a much larger island, which in turn is a few hundred km from mainland. The larger island is situated s

Actually looking at a map, the island is a mere 20km from a much larger island, which in turn is a few hundred km from mainland. The larger island is situated such that anything floating out to sea from the mainland has a 25% chance of hitting the larger island. From there, someone would find their way to the smaller island. Quite possible that some people floated out to North Sentinel Island in a confluence of events. Once there, if you don't have oars odds are you're not coming back if you leave (floating or swimming).