The Coolpix S31 has a CCD sensor type which is better than the MOS sensor type found on most waterproof cameras that were launched more than two years ago. 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 across all cameras of this type and age.
A MOS sensor type is the worst sensor type across similar types of digital camera.