The Mystery of Dolphin Inlet, by James Holding (epub/Kindle/pdf)

Pete Hobbs, a fisherman's son in the Florida Keys, and Susan Frost, a go-getter from Tallahassee, join forces one summer to investigate strange happenings in Dolphin Inlet. Their quest will ultimately lead them into danger -- with a sunken treasure as the ultimate reward...if they can find it -- and keep it! This book is one of two original Young Adult novels written by James Holding (the other being The Mystery of the False Fingertips). In addition, Holding wrote the Ellery Queen, Jr. mysteries, as well as nearly a dozen children's picture books, many with mystery themes.