The description alludes to the fact that it is a dive watch. Although I'm sure it is an excellent watch, it is not a watch for diving. 100 meters is only good for swimming at best.
3 ATM 30 meters/100 feet Everyday use. No swimming.
5 ATM 50 meters/165 feet Short periods of swimming. No diving or snorkeling.
10 ATM 100 meters/330 feet Swimming and snorkeling.
20 ATM 200 meters/660 feet High-impact water sports and some diving.
Diver 150-200 meters/500-660 feet Scuba diving. Passes ISO regulations.