This is an entertaining tome with an original method of storytelling and a certain sense of absurdity. A number of stories coalesce: the woes of what must be the world's least competent smugglers; a theologian determined to prove in 1857 that the Earth is only 6000 years old in the face of atheist geological evidence; a doctor researching human races; and a Tasmanian aborigine whose lifestyle and culture is destroyed by white settlers.
In the early parts of the book, the sections narrated by Captain Kewley and Peevay do seem rather drawn out, but these characters seem to develop as the book progresses. On the other hand, Reverend Wilson starts out most energetically, but his narration somewhat loses its way. Dr Potter's diary is written in a v. irritating Bridget-Jones style, though its subject matter is amusing in a disturbing kind of way.
The intellectual duels between Wilson and Potter on the journey are perhaps the most amusing sections, certainly very plausible of their melodramatic characters. It is quite some way into the book before the land expedition, to find the Garden of Eden in the Tasmanian wilderness, gets underway. The story never has a clear path ahead of it, and the suspense is generally well maintained. Even when there is perhaps a more obvious storyline to follow, one is never sure it will happen until it arrives. Though the tale is curiously amoral in many ways, it has to be said that all the principal characters probably get their just desserts by the end of the book.
I bought this as a random pick in a Waterstone's 3-for-2 offer a couple of years ago, and it was worth the risk.