This is not one of the best blocks at the Lost Crag, but there a couple of routes here worth mentioning.
From the Entrance Block, head left until you reach a very featured block with a crack feature splitting the face and a tunnel passage on the right side.
Browse More Classics in Tunnel Block
Mountain Project's determination of some of the classic, most popular, highest rated routes for Tunnel Block:
Center Crack 5.5 TR, 1 pitch
Slacker 5.6 Sport, 1 pitch
Unnamed 5.7 5.7 TR, 1 pitch
Unnamed 5.8+ 5.8+ TR, 1 pitch, 25 feet
Featured Route For Tunnel Block