Massacooramaan
Region of origin: Guyana
One of a class of malevolent spirits in Caribbean folklore known as jumbees, the massacooramaan is an ape-like boogeyman figure who attacks from rivers and other Guyanese bodies of water, upturning small boats and dragging people under the water to drown them before consuming them. It is believed the origins of the story may lie in escaped slaves who fled into the jungles and swamps of Guyana and were faced with surviving the rough waters of rivers they then had to cross.
The Compendium of Arcane Beasts and Critters 