BTW: The combat swim 500m and underwater standards go back to WWII. Its been an Army Ranger and Special Forces proficiency standard since 1952.
2x 25m underwaters: Pass
500m swim: 12 min 30 sec
The water skills assessment is a derivative of the determining of infantry soldiers swimming abilities during WWII at the Army’s 1942 designated amphibious training center, Camp Gordon Johnston near Wakulla Springs, Florida. With the Navy taking over the bulk of the amphibious landing training, Camp Gordon Johnston transitioned to a Special Forces Training Center in September 1943 emphasizing the training of provisional Commando task forces and preparing members of infantry units planned to be sent to fight in the wetlands and jungles of the Pacific Islands and Southeast Asia. Swimming instruction was provided for all troops not only because of the physical benefits to be derived from it but also to impart to men who had never learned to swim with enough skill to enable them to save themselves in case a landing craft got shot out from under them during an amphibious operation.