The transmitter (the part stuck to your body) is waterproof but the receiver (display device) is not. When I go to the beach, I usually put it in a waterproof camera case and wrap it up in a light colored towel so it doesn't get too warm in the sun. Enjoy your cruise, jealous as I look out the window at snow. Dan
Although the transmitter is waterproof, unless you get a waterproof bag for the receiver, you won't have readings during that time - and for my son sometimes if a little water gets under the transmitter it will stop working for a little, but then resume transmitting after it dries out.
I've used those before as durable food bags on backpacking trips. They weren't as durable as I had wished for, but they do last quite a while (at least 10x the life of a regular ziplock.) There's a kayaking company that makes a thicker one that I might go for, especially since it doesn't have text all over it.
I haven't bought that type yet, but I probably will these season once I start kayaking. I've seen them at sports stores here, and they seem very durable and would seal to be waterproof reliably. I'll report back later in the year when I know for sure.
I did have a few aloksaks, and used them for holding sandwiches and other food things in college. They are essentially a ziplock bag which is quite a bit thicker and has wider seams. They did last a while, but do wear through. They would probably be fine as a water repellent, like if you are in the rain or something splashing. I wouldn't rely on them for waterproofness though, like kayaking where it could potentially be submerged. Just my 2 cents.
A couple of days ago I learned that the California State Assembly is considering AB-1893 Sharps waste, which in (if approved) will mandate that: “Sharps sold to the general public in California shall be sold with a sharps waste container Read on! →