Admiral Harriman Nelson is evaluating the Neptune, a Navy ship very similar to the Seaview, during a voyage. The Neptune runs into a forcefield, which radiation readings are also detected in the area. As he remarked about wanting a sample to study, Nelson and a crew member don wetsuits and swim to an area on the ocean floor, which they remove part of a rock for study. They watch as the Neptune comes under attack by a giant jellyfish, which destroys the sub. Nelson and the crew member then swim up to the surface, take off their wet suits, inflate them with oxygen left over from their tanks and tie them together to make them into a makeshift raft. Nelson later catches a fish and begins the long journey back to land (which is 300 miles away), but the Neptune officer succumbs to either radiati