I'm trying to remember the name of a series that was probably from the 70's or 80's that involved a small group (made up of children?) who were travelling through a maze or network of tunnels with the help of a computerized map (which sort of reminded me of the Hitchhiker's Guide in a way).
- I think they were travelling in something like a mine cart or amusement part ride.
- I also recall there being someone — a young man — who was somehow advising them from afar
- but he was trapped under a waterfall and was covered in green clumps of something from the falls.
- He was eventually freed.
- And there was an enemy they were trying to outwit.