What part of swimming is aerobic and anaerobic?

When you are doing high-volume workouts, with a good amount of breathing, this is an aerobic swimming workout. Anaerobic swimming workouts have to do with sprinting. However, simply sprinting, even if it is on a pace clock, does not make the workout anaerobic. By extending the rest period, and demanding the maximal speed of the athlete during springs, is an anaerobic swimming workout.