Weird closing credits question

[Misfit]

Okay you know the old cartoon's closing credits where the turtles and April are standing 'frozen' somewhere underground while the credits roll? Am I the only one who's ever wondered what/where that undergound place is?

I tend to think it's the sewer's, but then wouldn't there be more pipes and stuff? It looks like it could be a large cave of some sort, that's a possibility.

Also was that picture in the closing credits actually a still from some cartoon episode? Like one of the early ones maybe? I never recall seeing April and the Turtles anywhere like that in the series, although it's been a very long time since I watched most episodes.

Weird question, I know, but for some reason it's really bugging me! I think I've got too much time on my hands! LOL.

Edit: Here's a pic to get a better idea of what I'm babbling on about: .



P.S Anyone else love the instrumental version of the theme song that's played at the end I think it's cool