Quote Originally Posted by euan View Post
I haven't used them, but they get a decent write up on some of the watch forums I look at.

I guess the key thing is if you want it pressure tested again to 200M - 50M basically means it's splash spoof, 200M means it won't get damaged if you properly dunk it.
Here's the "official" rating of the various levels of water resistance...

Water Resistant or 30 m Suitable for everyday use. Splash/rain resistant. Not suitable for swimming, snorkeling, water related work and fishing. Not suitable for diving.

Water Resistant 50 m Suitable for swimming, white water rafting, no snorkeling water related work, and fishing. Not suitable for diving.

Water Resistant 100 m Suitable for recreational surfing, swimming, snorkeling, sailing and water sports. Not suitable for diving.

Water Resistant 200 m Suitable for professional marine activity and serious surface water sports. Not suitable for diving.

Diver's 100 m Minimum ISO standard (ISO 6425) for scuba diving at depths Not suitable for saturation diving. Diver's 100 m and 150 m watches are generally old(er) watches.

Diver's 200 m or 300 m Suitable for scuba diving at depths Not suitable for saturation diving. Typical ratings for contemporary diver's watches.

Diver's 300+ m for mixed-gas diving Suitable for saturation diving (helium enriched environment). Watches designed for mixed-gas diving will have the DIVER’S WATCH L M FOR MIXED-GAS DIVING additional marking

My favourite though is for the ladies' Cartier watches, in the literature that comes with them owners are advised to be careful not to get perfume anywhere near the watch as it can damage the internals