nice idea, but too soft and a bit too over-exposed. this is a tough shot to meter and shoot--there are just so many things making it difficult. if you had found a different perspective where you could have zeroed in on one or two people's faces and caught their expressions amidst the spray.
Looks like everyone is having fun. Nice potential here. You have a nice composition with the raft coming into the frame and some good action going on. The motion has been stopped for the most part. On the downside, the lighting is very harsh and the image is overexposed. Looks like midday sun, so that is hard to get, especially with limited time for adjustments. Would have been better to slightly underexpose perhaps in this case and try to bring it back in post-processing. Once you've lost detail you can't recover it. Nice capture overall, just that darn lighting... Good luck in the challenge.
Composition is good, but the colors seem rather flat and highlights are blown out. The bright white invariably draws the eye away from the main subject, in this case, the people in the raft.