Wow, alot of cool ideas:
Tunnels would be very interesting, i had another interesting idea with use of cameras:
What about having the drive team in a box of some sort, there only inputs are a field spotter with a radio, and a cam on the bot?
Also another note to everyone here: We all know chances of water and ice are nill, but if you want to see it, pick it

I'm quite surprised this thread went so well so far! Alot of great ideas!