My workout partner has recently been having issues with shin splints, so I decided to join him aqua jogging to change up my cardio. However, it became extremely boring after about 5mins, so decided to turn it into HIIT. We did a lap as fast as possible (scew the proper technique, splash and kick everywhere and use as much energy as possible) then rest and repeat about 10 times.
The other (ancient) aquajoggers thought it was hilarious, and I got possibly one of the most awesome cardio session ever.
Just putting it out there as an idea for people with injuries that don't allow normal sprinting/sledding/prowlering (prowling?) and stuff :).