Try each exercise in 30-second sets with 30-seconds rest between exercises:
(10-minutes total)

1. Jog in place

Keep knees high.

2. Tick-tock hop

Quickly jump from side to side, keeping feet together.

3. Knee twist

Cross right elbow toward left knee at waist. Alternate sides.

4. Squat jump

Squat down with arms extended at shoulder height; jump as high as possible while raising arms overhead.

5. Jog in place

Keep knees high.

6. Bicycle

Lean with back against side of pool, arms outstretched at edge. “Pedal” legs at surface.

7. Flutter kick

Hold onto edge of pool, arms extended; kick legs quickly.

8. Pendulum swing

From bicycle, extend legs in front of you. Swing up and over to the right, then left, keeping them together and underwater.

9. Crunch

From bicycle, extend legs, keeping feet together. Pull both knees into chest. Return to starting position.

10. Outer-thigh lift

Stand with left side near wall, feet together, holding edge with left hand. Lift right leg out to side. Do 20 reps on each side.

Advanced athletes go 30-seconds 100% speed (fast and intense) and 30-seconds at 30% speed.