Workout

Warm-up (500)
2 rounds
100 swim/100 drill/50 kick

Set (600)
12 x 50 build on :45
…4 cb

Set (2100)
6 x 200 on 3:00
…Odd Hard on 2:30
6 x 100 on 1:30 
…descend 1-2
6 x 50 on 1:00
…odd FAST!
..even build

Cool-down (200)
200 easy