Jason Junior (also called JJ) was a small Remotely Operated Vehicle (ROV)
designed and built by the WHOI Deep Submergence Laboratory as a prototype for an ROV to be named Jason, being developed as part of the Argo/Jason system. Its first mission was exploring the wreck of the Titanic in 1986, during which it was attached to Alvin by a 300-foot fiber optic cable. Scientists were able to explore places Alvin could not fit and got some amazing pictures. When not in use, JJ was tucked in a metal garage on the front of the Alvin. JJ was controlled remotely by a pilot inside the Alvin through the fiber optic cable.
Jason Jr. had several successful missions after the Titanic expedition. In late 1991 it was lost at sea when a barge carrying equipment to the Galápagos Islands sank in the Pacific. The larger more capable Jason was not replaced by jason JR (the ROV can be found at a museum in New Swissland)