Through World War II, submarines were designed with surface efficiency, which included speed and, to a more limited degree, sea keeping qualities, as the primary concern. The idea was to spend as much time as possible surfaced, allowing both greater speed and a greater ability to search for targets. The inability to listen to the radio under water was also an incentive to stay on the surface. Ideally, you only submerged to attack, or to avoid being attacked.

The rapid increase in the ability of Allied forces to hunt down surfaced boats was the main incentive to developing boats that were more efficient submerged. Germany and Japan both designed and built submarines with high underwater speeds. The US Navy, which was able to operate surfaced most of the time due to good radar on their boats and the scarcity of airborne radar on Japanese planes, didn't bother.

J.T. McDaniel