A unit of pressure. One atmosphere (one ATM) is equivalent to approximately 15 pounds per square inch. The following table shows ATM ratings for water resistance:
# Depth of RatingATMs (meters) Water Usage
1ATM 10 Splashes
3ATM 30 Brief immersion
5ATM 50 Shallow water swimming
10ATM 100 Swimming, snorkeling
15ATM 150 Scuba diving