[EStokely]

Think outside the box.

I agree hovercrafts would be cool but....

Lets say wheels and treads are outlawed. Walking robots would become the norm, or would they?
What about a robot that rolls. like that Jimmy Neutron toy at Radio Shack. the whole exterior of the robot is the transport.
Its as useful as the hovercraft idea and use s much less battery power to run.

Or a jumping robot....

Or a snake drive....

you say water, who says it would be liquid? A skating robot.

Well that was fun
Eric