Workout

Warm up (600)
Swim 600
...every 4th 25 back

Set (450)
6 x 75 on 1:20
kick/drill/swim, 
kick/build/swim
kick/sprint/swim

Set (2000)
400, 300, 200, 100 x 2 rounds
400 on 5:45
300 on 4:15, 
200 on 2:45,
100 on 1:15.

Set (250)
75 mod, 50 sprint, 
75 mod, 2 x 25 sprint
...75s moderate on 1:15
...sprints on :30 per 25

Cool down (200)
200 easy