Just a diver casually swimming next to this absolute nightmare
The lion's mane jellyfish (Cyanea capillata) is one of the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. It is common in the English Channel, Irish Sea, North Sea, and in western Scandinavian waters.
The largest recorded specimen was measured off the coast of Massachusetts in 1865 and had a bell with a diameter of 210 centimetres (7 feet) and tentacles around 36.6 m (120 ft) long.