their training started in november 1943 at camp pendleton, california, moved to santa catalina island, california in january 1944, and finally moved to the warmer waters of the bahamas in march 1944. within the u.s. military, they pioneered flexible swimfins and diving masks, closed-circuit diving equipment (under the direction of dr. chris lambertsen), the use of swimmer delivery vehicles (a type of submersible), and combat swimming and limpet mine attacks.