With a little training, we can all swim underwater as freely as a fish. All we need is an aqualung, which consists of portable breathing equipment carried by the diver. The aqualung supplied air naturally as the diver breathes in and out. Wearing froglike fins, aqualung divers can swim quickly with little effort.
Before the aqualung was developed, divers had to wear bulky suits – which restricted movement – tethered by cable to boats on the surface. Jacques Cousteau, the famous French diver, invented the aqualung during World War II while fighting with the French resistance.