Even people that are not "survivalists" know that you wont last long in this world with out water. It will be one of the first thing you will need in any situation if you intend to live. Most people also know that you shouldn't drink sea water when you are in a survival situation as well because of the high salt content as it will only dehydrate you even more then you may already be.
There is something that probably not many of you know about sea water though. If it is frozen it is much less harmful to you then liquid sea water. When frozen the sea water contains only a tenth of the amount of salt that the liquid form does due to the fact that the salt is separated from the water when freezing as it does not fit into the crystalline structure of ice.
It is still not a great substitute for fresh water but frozen sea water is much better, and you can survive on it much longer, then liquid sea water. Obviously this only comes in handy in a very cold climate where even the cold can kill you if you don't have proper shelter but still knowing this just may save a life one day!