Workout

Warm-up
10 min easy swim

4 x 25 kick sprint on :45
2 x 50 kick sprint on 1:30
100 kick sprint 
100 easy swim

8 x 50 (25 Fly / 25 Free) or (25 no breath sprint / Free) at least 25sec 
rest

100 easy swim

5 x 100 Sprint on 2:30, any stroke 

Warm-down
500 (as 200 swim, 100 kick, 200 swim) easy