Fun Work Out! Try it

All Freestyle:
500yd warm up

5 x 100 on decreasing intervals ie:
#1: have fun
#2: cruisin'
#3: that was kinda fast
#4: yea I'm fast
#5: Smoking fast

using a pace clock works too, take 5 seconds rest off each as you speed up.

5 x broken 100s
Option 1, easier: 50 80-90% hard, 50 ridiculously easy
Option 2, harder: 75 80-90% hard, 25 ridiculously easy
Total pace should match either your have fun or cruisin' pace

500yd pyramid
25 easy
50 cruisin'
75 that was kinda fast
100 yea I'm fast (do this one twice)
75 twkf
50 c
25 e

Have a nice warm down and don't forget swimming is supposed to be fun.  Do some underwater somersaults or something.  Enjoy yourself.

-Matt