When I do water vacations, I use the Untethered Regimen with my pump. Essentially I take 75% of my basal using Lantus and use my pump for boluses and wear it overnight. It gives you the best of both worlds. You have the pump when you want it, but can leave it in your hotel room when you don’t. For added flexibility you can also use an insulin pen or vial/syringe with rapid insulin when you’re out on a boat if you want to leave your pump safe on dry land.
Here is a link to my blogpost about this. My post contains a link to a 2004 article by Steve Edelman who is credited with “inventing” this. Some athletes use this approach all of the time. I have tried doing that, but my basal rates are so low that it didn’t work well for me. But it has worked great for beach/boat vacations.
I followed @MarieB’s advice and ordered a sleek sleeve for those times that I am in the water and worry about losing my Dexcom transmitter. (I almost always use my upper arm for sensors.) In general you might have wonky sensor results if you are in the water for several hours, but remember that you can remove the transmitter, dry the underside and the contacts, and then put it back on.
Have a great vacation!