This tunnel is about 200 meters long. It is five feet four inches high. See MAP. The walls have been smoothed with the passing of thousands of slaves (and a few tourists) over the centuries. This tunnel leads to the quartz room and a subterranean lake which we discovered in a centuries-old shaft which had never been visited since the emancipation of the slaves in Brazil in 1888. The mine closed then as it became non-viable as a financial venture without slave labor.