My wife and I went down to Belize over winter break and I was looking for a camera to take snorkeling. Steve Gough (LRRD) had a recommendation of the Pentax WG90. Based on his description, this sounded like a good set of features, but Pentax had updated this camera to the WG-3. Based on my experiences so far, I can only say that Pentax's changes have improved their earlier design and make it even more useful for field work.
First, one version comes with built-in GPS tagging (didn't get that version, but I do plan on getting one for field work this summer with the GPS option). The 1 cm macro feature does a pretty good job of getting up close to the subject. It comes with 6 LED lights around the lens to help illumination at such short distances.
Ice crystals 1 - 2 cm long
White grains are about 1mm in diameter
Looking at reviews on Amazon, the only recurring complaint (not easily attributed to user error) seemed to be about the zoom mechanism failing. Given that I use this camera at its widest setting more than 90% of the time, I'm not too concerned about it. And so far after 3 months of heavy use, it's been fine.
But the best part of this camera has to be the fact that its waterproof. Pentax advertises it as waterproof down to 45 feet, but so far I've only managed to take it down to about 10 ft. It is important to rinse it off after taking it in salt water and dry it off before opening the battery door. Carefully wiping the rubber gasket and battery compartment to keep grit out helps maintain the water sealing.
Midnight Parrot Fish, Lighthouse Reef Atoll
To make the camera waterproof, all of the moving parts are sealed behind plastic or metal. This means no small joints or slots where dirt can get in either. Cleaning the camera is basically dunking it in a stream or rinsing under the faucet. A lens cloth to polish the front of the lens helps eliminate smudges or water spots.
I'm still coming up with ideas for teaching and research in sedimentology/hydrology using the video capabilities. Here's a rather long (10 min) video showing some examples of important sedimentology concepts:
Sedimentology using the Pentax WG-3 from Matt Kuchta on Vimeo.