If you've not already seen it, you can follow the adventures of Charles Darwin, who is posting updates of his voyage as @cdarwin on Twitter. (Delayed by 181 years, naturally):
Geologist, naturalist and gentleman. On board The
Beagle with Capt Fitzroy on a voyage around the world.
It's a five year voyage (near enough) and comes highly recommended. He's only just on board, so plenty of time to catch up.