Most rivers flow into an ocean or a larger sea, but the Okavango River in Africa is a major exception. Instead of reaching the coast, it flows into the Kalahari Desert, where it creates the Okavango Delta. This is one of the world's largest 'endorheic' basins—a drainage system with no outlet to the sea. During the dry season, the water simply evaporates or seeps into the desert sands. This creates a unique oasis that supports an incredible density of wildlife in the middle of an arid region. The delta’s flooding cycle is the opposite of the local rain cycle, as the water takes months to travel from the Angolan highlands to the desert flats, meaning it provides water when the rest of the region is driest.