PORTLAND, Maine – As Portland celebrates tall ships weekend, there are some who believe tall ships aren’t the only things at home in Casco Bay.

For centuries, people have claimed to see sea monsters in Maine’s waters, with an unusual spike in such sightings, 200 years ago this summer.

Sea monster stories and sightings go back centuries, including a famous one involving Maine naval hero Commodore Edward Preble, giving chase to one in 1779.

In the long history of Maine sea monster sightings one summer stands out, 1817.

The descriptions were always similar, and everyone seemed to agree it was big.

A new exhibit at Portland’s International Cryptozoology Museum is dedicated to the sea monster hysteria of 1817.

As for the spike in sightings in 1817, they would continue through 1818 and 1819 as well, before dying down again, but not before the Royal Society of London actually dispatched a team of investigators to Casco Bay to try to get to the bottom of this murky mystery.