The Loch Ness Monster isn't the only mysterious creature to live in a lake. Issie is a cryptid, inhabiting the murky depths of Japan's Lake Ikeda.

One of the earliest reported sightings of Issie occurred in the spring of 1978. That fall, three children playing on the lake's shore reported seeing a creature with two large black humps slipping through otherwise perfectly still water. Twenty people experienced the same sighting, all describing humps measuring over fifteen feet and extending approximately two feet over the surface of the water. One of those 20 people tried to pursue the creature in a motorboat, but it was crossing the lake at a speed that kept him from catching up.

Since Lake Ikeda rests in the caldera of an extinct volcano, its water only comes from underground sources and rainwater. This begs the question, how did a creature like Issie get into the lake? Malaysian eels were introduced into the ecosystem years before, but they can't account for Issie. The largest eel that has yet to be spotted in the lake is a little over five feet long. No creature known to live in the lake is big enough to explain the sightings.