What you may well know as a titillating trashy film starring Brooke Shields and Christopher Atkins* from your pubescent years is also actually a book from 1908 about two young people falling in love. They were shipwrecked and then their hormones kicked in. I think it was filmed in Fiji.
"And the experienced a love as timeless and as powerful as the passing of the seasons...."
*whatever happened to Christopher Atkins?
Paperback good condition (covered in contact, so diligent, so diligent former owner)
Futura Publications, film tie in, 1980