Please Register or Log in to view the hidden image! This isn't Risa... I knew that I shoulda taken that left turn at Aldebaran!
I presume that scene is from the 2nd TOS pilot. But Risa wasn't mentioned until TNG. It's funny though. Alan Dean Foster has aliens in his Pip & Flinx series that can dig tunnels from one planet to another. See Flinx in Flux.
Even though it isn't mentioned, it's not to say it didn't exist during the TOS era. I quess I could have used Wrigley's Pleasure Planet, but it just didn't seem to be the kind of place Bugs would visit. Speaking of tunnels, The "Devil" in the Dark: Please Register or Log in to view the hidden image!