There is a lake that's also a waterfall - Apparently.
Lake Agrio, located in Colombia, is a lake that flows upwards into a cave, creating a waterfall effect. The lake is situated in a unique geological formation, where the water flows from the lake into a cave, then falls back down into the lake, creating a continuous loop. This phenomenon is due to the lake's connection to the nearby Magdalena River, which feeds the lake and also drains it, creating a constant flow of water upwards into the cave.