The Ricoh WG-20 has a better sensor type than most waterproof cameras that have been on the market for around the same time as it. This camera has a CCD sensor type, whereas most cameras of a similar spec and age to it 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.
This digital camera's sensor type (CCD) is in fact the best sensor type amongst all waterproof cameras that came out more than two years ago.
The worst sensor type amongst similar types of digital camera is MOS.