I use a Breitling Avenger Seawolf. It's solid titanium with a doubly-multi-coated sapphire crystal, and is waterproof to 3000 m (10000 ft). The movement is a certified chronometer, and self-winding.

It's likely to survive in conditions much worse than any I expect to face.

The only trouble is remembering to keep it wound if I take it off for more than a day, and getting it serviced every couple of years.