i train in a pool maybe once a week or every two weeks. theres alot you can do with a pool. especially sometimes when i travel for work, theres cardio machines and a pool, but no weights.
bottom line = be creative. try experimenting doing various kicks and punches in the pool. I do lengths of the pool doing single kicks, combination kicks, and punch/kick combos. I also practive judo sweeps, "uchikomi" entries, even single leg and double leg motions (easier on the knees!).
my condo pool is about chest deep the entire length, but if you have a deep and shallow end, you'll have to find the best part to use.
I also sometimes swim sprints, in between my sets of kicks, punches, or grappling moves. finally to finish off my pool workout, i do 3 exercises: 1) rush and push away against the wall of the pool, 2) tricep dips in the corner, 3) sitting at the edge of the pool -- legs in the water -- V-ups. The water adds resistance.