Mount Otemanu, Bora Bora. It's impossible to climb to the summit because of the brittle volcanic rock which is too fragile to hold a person's weight. According to the locals, nobody has EVER successfully scaled the top. You can, however, take a hike up to the base. The path is confusing and the jungle is thick so it's recommended to take a guide or a 4x4 tour. Here you will find leftover US cannons from World War II and scattered altars from the ancient past.