As an added bonus... it's FUN!
Doing Co2 tables and static holds in your bed can get boring and repetitious.
UWH will condition your legs to repeated sprints (at each faceoff) and condition higher levels of Co2 and lactic acid. This is GREAT for fighting the surf while spearfishing or for a long ascent after a CWT dive.
Note that if you're lucky enough to score a breakaway / hard-fought battle for the puck or score a goal (like I did in the last 5 goals in the vid below), then you have the "privilege" of swimming all the way back to your side and then racing for the puck in the middle again, as I did in the beginning of the video at centre. Did I mention that it was good for lactic tolerance and leg conditioning??