Operation Tracer

Operation Tracer was a top-secret WW2 mission in which a British team consisting of 6 men were to be sealed in a cave inside the Rock of Gibraltar, incase Nazi's captured Gibraltar. They were to monitor enemy movements after the Rock’s capture. They would have supplies with them for several years as there was no way out and anyone who died within the chamber would have to be embalmed and cemented into the floor. After decades of rumors and searching, the cave was rediscovered in 1997.