By Guardian Staff Footage shows swarms of barrel jellyfish (Rhizostoma pulmo) off the coast of Cornwall in the UK. The video, taken by a local wildlife enthusiast Ross Wheeler on Wednesday from a boat near Falmouth Harbour, shows the jellyfish gliding through calm water. This swarm of barrel jellyfish, which can grow up to six feet long, was reportedly a mile long

Via: http://www.theguardian.com/science/video/2015/apr/17/barrel-jellyfish-swarm-coast-cornwall-uk-video