Below is a list of lake monsters that have been reported worldwide in lakes, reservoirs, ponds and marshes. River monsters and lagoon monsters are not included, nor are confirmed hoaxes and misidentifications, though most of the creatures listed here lack any scientific basis.
About twenty-five feet long, with a tail which tapers until within about five feet of the end, where it broadens out to look much like a whale. Its head is approximately four feet long and triangular in shape. Its mouth is very long and was armed with two rows of triangular white teeth as sharp as those of a shark, but in shape more like those of a sperm whale. Its body is covered with a horny substance which is as much like the carapace of a terrapin which is brown in color and of a greenish tinge. Its eyes are round like those of a fish. (The Geneva Gazette, July 15, 1899 account by George R. Elwood, Geologist)
Possibly related to "Old Greeny" found in Cayuga Lake, Ithaca, NY
A sea serpent or eel-like creature. Sightings approximate length from 13–35 feet. Multiple accounts of sightings reported in the Ithaca Journal from 1887 - 1979. It is believed that the creature may be related to the Seneca Lake serpent.
Sightings began in 1828 shortly after the lake was connected with the Erie Canal. Because of the lake's connection to the Canal, it is believed that the monster may be some sort of a sea creature.
Coleman, Loren; Huyghe, Patrick (2003). "Appendix". The Field Guide to Lake Monsters, Sea Serpents, and Other Mystery Denizens of the Deep. Trumbore, Harry; Lee Rollins, Mark. New York, New York: Penguin Group. p. 358. ISBN1-58542-252-5.