I use a MiniMed, which is supposed to be waterproof, but last summer got dunked in the pool for just a second (my young son jumped on me and sunk us both) and pump stopped working.
MiniMed pumps are not waterproof. They are water resistent. Medtronic even warns about that. So, by no means, try to submerge your pump in water without a proven waterproof casing. Also, I do advise that whatever waterproof case you decide to get, be sure to read ALL of the instructions on how to use it properly because when I got the SportGuard, I didn't read the instructions at first and just figured out how to put together, but then when I read the instructions, it recommended that you use a bit of vaseline in the hole you slide the tubing through. This creates more of a watertight seal, otherwise it is possible to get water leakage in the case when submerged for a long period of time.
Also, Brianna, I agree with everyone else that swimming does lower your blood sugars. However, I just feel safer staying attached to my pump while in the water for a long time. I would set a lower temp basal and make sure I have access to snacks on the boat for afterwards b/c you will need to replenish your energy. Don't stray far from your husband either since he knows you and your diabetes. I have to admit that once while my husband and I were snorkeling, I was having so much fun that I didn't really notice that I was coming down. But my husband who was nearby notice that I stopped swimming around and that I was just floating there staring at the same coral for a minute. So, he came over and asked if I needed to eat something. Turned out that I actually needed to rehydrate.