Definitions for "Bottom Time"
Keywords:  ascent, diver, dive, descends, padi
Bottom time is the physical time spent underwater from the moment one descends, until one starts ones “direct” ascent to the surface. Used in dive table calculations, such as the PADI Recreational Dive Planner.
The amount of time from getting in the water at the start of a dive until the beginning of the ascent.
the time between descending below the surface to the beginning of ascent.