Thinking I only had one day left in TX, we made a dash across the state to do the biggest tunnel we could find. we arrived on site at 11pm, curfew for making it back to Houston for my flight was 3am.
With time against us we popped the tiny gutterbox manhole, dropped around 45kg of ropes, ascending gear, our cameras and other items and started the squeeze through 3ft RCP to out first vertical RCP.
Maneuvering out into the first box section, I was expecting a 30ft drop. This turned out to be more like a 20-30m drop. We had one 70m dynamic rope and some walmart 1/2" marine rope on a spool. Horrendously ill prepared, we were debating whether we would even make it to the main tunnel, but decided to commit and were rewarded accordingly.
Thanks to the people that convinced us to go back