Can't get it to work, also a spoiler.
Is this the tunnel? I found a pile of dirt above it, which gives me 100 coins, but other than that I can't figure out how to "dig" through it. There's no commands anywhere near the rock.
I dont know how to mark things as spoiler sorry.
Anyway no that is not the tunnel. It is supposed to be a fallen tree. When you leave the town head to the right and just follow the wall until you see a fallen hollowed out tree. The path is blocked by dirt.
It should be easier to find after you unlocked the beegirl and her hive.