One of only two cameras that fall under the standard point and shoot underwater camera category (Olympus MJU 725 SW being the other), if you want to take pictures of your friends by the pool you don't have much choice. However, the W20 isn't a bad camera and alongside the JIS Class 8 water proofing, JIS Class 5 dust proofing, has the standard features expected from a camera of this type at this price. The W20 can be submerged underwater up to a depth of 1.5 meters for up to 30 minutes continuously.
The W20 is the replacement to the W10 and improvements come in the form of an increase in megapixels from 6 to 7, a higher maximum ISO sensitivity (1600), and improved anti-shake/anti-blur capabilities. The W20 also contains an SDHC slot whereas the W10 does not.
As of February 2007, the W20 has been replaced by the Pentax Optio W30.