Except in pool floats, closed-cell foam has a number of very important uses, including:
Life-Saving Rings Buoys. Closed-cell foam is ideal for creating life-saving rings. Since the stuff won’t deflate and is amazingly buoyant, as soon as you can get one under a panicky swimmer then at least half your troubles are over because this stuff just will not go down. That unsinkable property also makes this stuff a shoo-in for safety marker supports and buoys. It wears well, too, making it through several seasons before needing replacement.
Life Jackets. If you love boating, then closed-cell foam is your friend. Boats and life jackets are two things that go together, and when the life jacket is made from closed-cell foam, “man overboard” isn’t nearly as panicky a thing as it might be. There was once a young couple who took their two-year-old with them on a float trip. Of course, their canoe turned over and everything in it took a dunking including the baby. Fortunately, he was wearing a closed foam life vest and went bobbing downstream where he was quickly recovered by some fishermen. His parents were terrified and panicked, but he was happy as a little fish having gone for a good swim and having made some new friends.