The Ricoh WG-20 has a better sensor type than most waterproof cameras that came out more than two years ago. This Ricoh digital camera has a CCD sensor type, whereas most cameras of this type and age have a MOS sensor type. CCD sensors produce high quality, low-noise images but consume a lot more power than CMOS sensors. CCD is the most common image sensor type used in digital cameras.
A CCD sensor type is actually the best sensor type amongst all waterproof cameras that were released around the same time as the WG-20.
A MOS sensor type is the worst sensor type amongst similar types of camera.
Other cameras that have a CCD sensor currently available which you might also want to look at include because of it's better review score, the Panasonic Lumix DMC-FT3, or the Nikon Coolpix S31.