Into the open ocean

Open-ocean SCUBA diving from research vessels began to reveal more about the world of jellies during cruises in the 1970s. To make their collections and observations and avoid becoming lost in the vast ocean, the divers use a tether system, with one person serving as “safety” at its apex. Underwater lights enable them to make night dives to view and collect jellies when many species are more active and appear in greater numbers.(Photo by Larry Madin, Woods Hole Oceanographic Institution)