Barbara Hodgson's Hippolyte's Island (Chronicle Books, 2001), is a delight. I picked it up for the illustrations (lovely maps, drawings, natural history specimens, &c.), and half-expected the text to be nothing special. But I quickly found myself drawn into the story, in which the decidedly unorthodox protagonist Hippolyte Webb decides to go in search of the Aurora Islands, a mythical[?] mini-archipelago in the South Atlantic 'discovered' in 1762 and sporadically from then until 1862, but not observed since.
Hodgson uses Webb to spin a lively and fascinating web (heh) of a tale as we see him learn to sail, make his trek, and then try to convince his New York editor (along with everyone else, including the reader) that he's not barking mad. Using conventional narrative along with other devices (publishing-house memos, handwritten drafts, log excerpts), the book is paced well, and designed excellently.
A bit more character development wouldn't have gone amiss - while we get to know Webb fairly well, the others he meets along the way remain a bit sketchy. Perhaps that's intended, though. Either way, a fun read, with a fascinating quest at its heart.