We had some of these a little while ago so I was prepared for this as soon as I saw the nice calm picture. I turned the sound off as well, because the other ones had really loud scary noises which scared me more than the picture, so I don't know if this had sound or not. NOT FOR THE FAINT-HEARTED!
Erm...it's 2 peaceful aerial views of a river - as you peer intently at them they suddenly disappear to be replaced by a scary face & a horror movie sound effect (which I didn't know about...)
Definite error of judgment on my part - it made me jump & then giggle, but a) I hadn't realised about the sound (which definitely tips it over the edge from quite funny into bloody scary) & b) I just didn't stop to think there might be kids peeping over mum's shoulders! Stupid of me. Sorry.