A picture shows a jellyfish in the port of Ginostra on June 16, 2016, on the island of Stromboli. GABRIEL BOUYS/AFP/Getty Images

Two divers had a chance encounter with a rarely-seen species of a barrel jellyfish, Rhizostoma pulmo.

Lizzie Daly, a biologist, and Dan Abbott, an underwater cinematographer, were able to film the event and posted it in a Facebook post in support of the Wild Ocean Week campaign. This campaign aims to raise funds for the United Kingdom's Marine Conservation Society that includes a series of videos that demonstrate the uniqueness of the deep.

The two divers saw the giant jelly emerge from the murky water during their escapade off the coast of Cornwall, U.K. This species is commonly known as dustbin-lid jellyfish and has eight puffy arms that are surrounded by tentacles that sting and a large, globular head. It is common for this species to wash up on the shore but uncommon for divers to face them head to head.

"While the barrel jellyfish is the largest species of jelly found in U.K. waters, it's a mere shrimp when compared to the lion's mane jellyfish (Cyanea capillata), the largest known species in the world. This coldwater jelly is known for its galaxy of 1,200 long, trailing tentacles, which can bring an individual creature's total body length to up to 120 feet (36.5 meters) — which is longer than the average blue whale," according to Live Science.