4. North Sentinel Island, Andaman Islands
The island is small and covered in greenery but the coral reefs around it make it difficult to reach on water vehicles. Helicopters may have been able to access the remote island, but the obstacle, in this case, is not the environment of the island, but its inhabitants. The Sentinelese, the people living on the island are known to be hostile to outsiders. They reject outside contact so fiercely that they have been known to shoot at helicopters with arrows. Their tribe remains cut from the modern world and lifestyle and they intend to keep it that way.