Another great design in terrific colours. I kind of wish there was less of the black gap in the middles, but that's all. I'm not sure about the title - this doesn't have the closed-in, claustrophobic feel the title suggests to me. But that could just be me misinterpreting the title.
Most of all I like the sense of depth here... And, of course, those colors... The tunnel on top, though, gives it a bit of claustrophobia. Very nice touch.