Water, water everywhere, and nary a drop to drink. That's the ocean, and it's pretty big. Even if you're stranded out in the middle of the sea, you can't drink seawater, because it's so salty that it can poison your body. Most of the water on earth is seawater, and with climate change, fresh water is getting somewhat scarce in places where people need it. That's why there are more and more desalination plants every year, working to provide fresh drinking water but also contributing to the problem by using fossil fuels. Meanwhile, if you ever find yourself stranded out at sea, this TED-Ed lesson has a few tips on how to obtain fresh water, either from rain or dew, or from the blood and organs of certain sea creatures. To the person who doesn't have it, fresh water is more valuable than anything.