SEALAB I was lowered off the coast of Bermuda on July 20, 1964 to a depth of below the ocean surface. It was constructed from two converted floats and held in place with axles from railroad cars. The experiment involved four divers (LCDR Robert Thompson, MC; Gunners Mate First Class Lester Anderson, Chief Quartermaster Robert A. Barth, and Chief Hospital Corpsman Sanders Manning), who were to stay submerged for three weeks. The experiment was halted after 11 days due to an approaching tropical storm. SEALAB I demonstrated problems with high humidity, temperature control, and verbal communication in the helium atmosphere.