Getting a good signal lock can be a pain. :^)
Actually the gps usually takes you to an entrance, and some kind of markers will point you in the right direction when tunnels branch. You then find a spot with new coords for another tunnel, or you find a puzzle that solves to give you those coords.
The best stream tunnels in urban areas are usually around the intersections of major highways -- especially some of the complex intersections where several routes intersect. Sometimes a stream will just disappear into one of those mazes and emerge some distance away on the other side of the exchange.
--- In CentralTexasGeocachers@yahoogroups.com, Elise Taylor <elise_t@...> wrote:
> ..... I could see it being tough to get the GPS signal though!