Tour what's left of S.F.'s forgotten coal mine
http://www.sfgate.com/bayarea/article/Tour-what-s-left-of-SF-s-forgotten-coal-mine-6587426.php
Coal was discovered in the city! An old miner had found a vein hugging the coastline at Baker Beach.
"Do try to buy up that land," the "grizzly old miner," Charles Jackson, told Superintendent H.H. Lynch of the Cliff House and Ferries Railway. "There is a fortune in it, for I am sure there are thousands of tons of good coal in that district."...
Today the story of San Francisco's coal mine is largely forgotten. The tunnel is still there, although in decaying condition, thanks to decades of erosion. Mudslides, earthquakes and storms have collapsed portions of the tunnel and nearly buried its eastern opening.
Accessing the tunnel is no picnic, as photo-journalist Sierra Hartman can tell you. Technical climbing and careful attention to tides is required. Hartman turned spelunker and ventured into the shaft for a photo essay that appeared on the site Atlas Obscura.