Workout

Warm-up (500)
300 swim
4 x 50 dolphin kick
 
Set (600)
4 rounds
25 under on :30
50 EZ on 1:00
25 FAST on :30
...NB swim 
50 EZ on 1:00

Set (600)
2 x 100's on 1:45
...25 sprint/50 ez/
25 sprint
…then
6 x 50 build on 1:00
100 FAST  

Set (300)
Pull 300 3cb

Cool-down (400)
400 EZ choice