Lizzie Daly and photographer Dan Abbott came across an incredible sight off the coast of Cornwall. The lucky divers were able to swim with a giant Barrel jellyfish, according to BBC News.
Daly, a biologist with Wild Ocean Week, said that the creature was bigger than her body measuring an estimated 5 feet long.
The Barrel Jellyfish is the largest species of jellyfish. They have an average diameter of about 40cm (16 inches).