The Underwater Waterfall of Mauritius
Almost 2,000 kilometers (1,200 mi) off the southeast coast of Africa lies the Republic of Mauritius. First visited by Arab and Portuguese sailors during medieval times, the island was initially inhabited by the Dutch in 1638, naming it after Prince Maurice van Nassau. Successively, Mauritius became the subject of both French and British rule, with the country becoming an independent Commonwealth in 1968 and ultimately a republic in 1992.
Whoever governed this tropical island nation in the Indian Ocean got an amazing geographical feature as a bonus: at the southwestern tip of the island lies an underwater depression, creating a channel for sand and sediment to be deposited. When this runoff is viewed from above, the illusion of an underwater waterfall is created; the island itself appearing to swirl away into the depths.
Fun Fact: the towering summit standing over the "waterfall" is Le Morne Brabant, a basaltic monolith with its own claim to fame. During the 18th and early parts of the 19th centuries, Le Morne was used as a shelter by runaway slaves, "maroons" who built settlements atop the sheer, wooded cliffs of the mountain. There was a large enough population of escaped slaves that Mauritius was commonly known as the "Maroon Republic" during that time, and today the Le Morne Brabant peninsula is recognized as a World Heritage Site by UNESCO.