Underwater breathing would change raids more than engines

How would the world wars change if, from 1900, humans could breathe but could not eat or drink underwater at any depth their bodies could survive?

Submarine layouts and commando operations would change, but engines, batteries, cold, currents, and waterproof equipment would still prevent effortless underwater warfare.

The premise gives people underwater breathing at depths their bodies can survive, while leaving them unable to eat or drink underwater. Under those assumptions, more submarine controls and crew positions could sit outside a dry pressure hull, reducing the internal volume needed for people. Engines would still need air and batteries would still need protection from water, while exposed crews would face cold. Shallow straits would become more vulnerable to commando raids, and river crossings would change. The English Channel's depth, currents and soft seabed would still make a mass infantry crossing difficult. Weapons and other equipment would also need waterproofing.