Cut the cherries in half and remove the pits. Add them to a small saucepan on medium heat along with the water, sugar, and vanilla extract.

Once the mixture has been bubbling for about 5 minutes, mash the cherries (I actually used a potato masher to do this... use whatever you think will work). 

Continue simmering them on the same heat for another 10 minutes. 

Take the pan off the heat and let it cool for 15 minutes prior to straining it (use a sieve) into a jar. 

You can let it cool a bit further, or add some to a glass with ice and top it off with soda water. The syrup will keep in the fridge for about a week.