Japanese tunnels near Blacks Link (2010-02-15 #1) [????- ]
This is a bit unusual, in that the first section into the hill is wider than usual. It soon narrows though.
The other thing that is unusual is that there's a mound of spoil from the excavation just in front of the tunnel. Typically there isn't much sign of the spoil, and I've assumed it they's moved it away so it didn't show up in aerial photos.
Perhaps this was dug by a different group, or dug very late in the occupation and was a work in progress?
Here's the view inside: