A few weekends ago with my family went to a beach in northern Chile (Temblador Beach, La Serena), the place is very beautiful and peaceful. Driving on the beach I could see traces (Garbage) of previous visitors, then came to my mind, as could transform salt water (sea) in fresh water (drinkable) with the residues found. 

So the first thing was to collect material:

-Can Beer

-Plastic Bottle

-Wood

- And My RangerGrip 179, Patagonian expedition race

The first was to use the can opener to remove the top of the beer can, then make a hole in the bottle with a diameter equal to the diameter of the can of beer.

Then fill the can with sea water and inserted into the hole of the bottle (which should be leaning).

With the wood I made a fire to boil the salt water, which in turn causes water vapor (sweet), and this happened to accumulate liquid water, which moved through the bottle up to the mouth of the Bottle (For the inclination), which was collected in a plastic container, this way you can get fresh water from seawater. Hope you like