R. M. Ballantyne 
Coral Island 

A teenaged boy that goes by "Ralph" is from a long family line seamen. As he gets older his desire for freedom on the sea grows. He is finally allowed to go to sea. He meets two other boys, Jack and Peterkin. Jack being older than Ralph, and Peterkin being younger than him. The three become best friends and are shipwrecked on a Pacific Island and are all alone to fend for themselves. They explore the island and start making it their home. As they do so, they start making surprising discoveries, and are almost always facing dangers. (Amazon)