Tuvalu is made up entirely of atolls

The special thing about Tuvalu you should know is that Tuvalu is made up entirely of atolls. While many island countries often have some islands that are coral atolls, there are only four countries in the world made up entirely of coral atolls: Tuvalu, Marshall Islands, Kiribati, and the Maldives. Atolls are the remains of a volcano that has sunk below the surface of the water. The surrounding coral reef is all that remains of the former island. Atolls are long, narrow islands and are very close to sea level.

Most of the islands of Funafuti have a single road that just goes from one end of the narrow island to the other. On one side of the road is the ocean and on the other side is the lagoon. The theory of coral atoll formation was developed by Charles Darwin and a team came to Tuvalu in the late 19th century to drill on the island to verify the theory.