The seafloor has a diverse landscape, which includes underwater lakes and rivers. How is that possible? Well, these lakes and rivers form when seawater seeps up through thick layers of salt, which are present beneath the seafloor. As the water seeps up, it dissolves the salt layer, causing it to collapse and form depressions. The dissolved salt makes the water denser, and because it is denser than the water around it, it will settle into the depressions, forming a river or lake. Part of the "Deep Sea Dive" series.