Dolphin Island — Arthur C. Clarke

A science fiction adventure for readers of all ages, from a winner of multiple Nebula and Hugo Awards.
 
In the near future, a cargo hovership makes an emergency landing in a rural part of the Midwest. An adventurous teenager, Johnny Clinton sneaks on board -- only to survive a second crash a few hours later, this time into the Pacific Ocean . . .
 
The crew escapes, but Johnny is left on board, adrift in the wreckage of the ship -- until he is rescued by a pod of dolphins, who bring him to a remote island hidden in the heart of Australia's Great Barrier Reef. There, Johnny meets the brilliant and eccentric Professor Kazan, who has dedicated his life to the study of dolphin communication. Here in this new world, Johnny will find his courage tested once again . . .