About the Origins of the French Polynesian Atolls?

Most of the islands in French Polynesia are volcanic in origin and were formed by the clashing of the Pacific, Indian, Eurasian, and Philippine tectonic plates. The clashes forced up magma into the ocean, which cooled to create islands. Over time, the sea washing up against the island slowly erodes it, causing an atoll to form. Usually, in an atoll you will find beautiful coral reefs and protected anchorages if the entrance is navigable.  Entrances are often not visible until you’re very close, which makes them difficult to navigate.  It also makes the entry and departure time for most islands of French Polynesia particularly important. Coral is strong and sharp and can pierce the bottom of a wooden or fiberglass boat. Most boaters therefore choose to enter in the morning when the sun shines bright enough at a good angle so you can see deep into the water, allowing for navigation through the coral.