How do cetaceans find their way underwater?

Cetaceans do not have great eyesight.  However, their hearing is exceptional and like bats, they use echolocation to find their way around underwater.  It is primarily the toothed whales that use echolocation.  They send out sounds which travel and bounce off objects at a distance.  This tells the animal the size, shape, and distance of the object.  Their hearing is so good that they can tell the difference between prey and non-prey and they can hear sounds from dozens of kilometers (miles) away.