Lanzarote
The Spanish island where Karl spent his Christmas holiday in 2003, causing him to miss two episodes of Xfm Series 3. Prior to his trip, listeners informed him that Lanzarote (or, as one listener put it, "Lanza-grotty") isn't a particularly pleasant place to spend a vacation, as it is a fairly barren, volcanic island.
Lanzarote is home to 36 volcanoes. Karl suggested that they "keep a couple and fill the rest in."