"Apfelschorle" (also "Apfelsaftschorle") is a popular soft drink in Switzerland, Germany and Austria that consists of carbonated mineral water and apple juice. The broader category "Fruchtschorle" (fruit spritzer) consists of any fruit juice mixed with carbonated water, but "Apfelschorle" is by far the most common.
"Apfelschorle" contains fewer calories and is less sweet than pure apple juice. It is also nearly isotonic. This makes it popular in summer and among athletes.