Radio waves as low as 10kHz are used for communication with submarines.

Rifle-barrelled cannon

Submarines

Ironclad steamships

Large troop-movements by rail

Communication by telegraph

Sound waves travel very well in water. Warships, including submarines, use passive sonar to listen for enemy ships and submarines. Passive sonar employes underwater hydrophones to listen for sounds. They can detect sounds of ships and submarines miles away. Marine mamals such as whales and dolphins detect sound in much the same way.

1. Ballistic submarines

2. Attack submarines

Boats, Subs, Submarines, Home.