All dive watches need a depth rating of at least 200m. While very few divers see those sorts of depths as even a vague possibility, the rating remains important. The designation refers not to realistic depths but to realistic pressures the watch may have to endure when worn by any recreational diver. If 200m is converted into pressure it is roughly the same as 20 atm, and a diver moving quickly at recreational diving depths can reach pressures of up to 20 atm.