I got that it was their imagination, I think, and so it wasn't really Rio (or wherever), but I was completely lost as to where they actually were. (I only read the first one as well, although I loved it.)

Six books is not enough for a two-week holiday. When I was about 14 we went to France for two weeks, and despite taking about twenty books, I had run out halfway through the second week and started having feverish, anxiety-fuelled dreams about libraries. I was strongly considering cycling to the nearest town and ensconcing myself in their library, despite my very basic French literacy.