Sorry to be picky, but Tang was a Balao-class boat, not a Gato. This is significant because the Balao's were much stronger. The Balao's are often quoted as having an operational depth (test depth) of 400 feet. This would have been set at 450 feet, except for a trim pump that was copied from a German WW1 design, which could not function efficiently below 400 feet. Once the pump was replaced by a Gould centrifugal pump, McKee (an influential designer) felt the boats were safe to operate at 600 feet, but cautioned that some commanders were overconfident in thinking they could take their boats to 1000 feet.

Electric Boat and Manitowoc built Balao's with 35lb (7/8 inch) HTS steel, and these were rated for a 900-foot crush depth. Not too shabby.

Crush depth for the Gatos (9/16 inch of mild steel) was only about 500 feet, so operational depth (test depth) was held to 300 feet.