Weather Balloon Question

I was reading a copy of Popular Mechanics at lunch and saw an ad for an all weather camera that they attached to a weather balloon. This balloon goes so high you can see the curvature of the earth. You've probably seen stuff about people doing this.

My question, how do they retrieve these balloons? There's no way they come down anywhere close to where they were launched.

I'm sure that the learned gentleman of FABO can answer this one, and help out a not so learned one...lol.