As OBG mentioned, the water was the key to getting it to expand to such a large size. However, it still could be stretched on dry land though not nearly as far and not so easily. I just made mention of it as an illustration of how far they could expand and how tough they were. I should also mention that when our friend got in it, we could no longer drag it through the water and so it stuck to him pretty tightly.

In cold water, he probably could have... Ummm... Urinated in it, and kept some heat next to his body. Then again, it would be near impossible to stay afloat without a life jacket. <<Don't try this at home>>