One trip down the pool.

One or more lengths. A new interval starts after you rest.

A stroke is counted every time your arm wearing the device completes a full cycle.

Your swolf score is the sum of the time for one length and the number of strokes for that length. For example, 30 seconds plus 15 strokes equals a swolf score of 45. Swolf is a measurement of swimming efficiency and, like golf, a lower score is better.