You can reach Tarrey Town Tunnel through the opening in the southwest part of the cliff that Tarrey Town is built on.
Cave Location
The entrance to Tarrey Town Tunnel is at 3925, 1575, 0110, in the southwest part of the cliff that Tarrey Town is built on. You can glide there from the railcar station of the town.
Cave Features
Tarrey Town Tunnel is a straightforward tunnel with some ore deposits and Brightbloom Seeds. At the end of the tunnel, there is a short round platform, and behind that platform, you will find the cave's Bubbulfrog. You can Ascend while standing on the round platform to reach the storeroom of Hudson Construction. You will need to do so during the quest Mattison's Independence and remove the Hudson sign that is blocking the storeroom door, then go through the door so Rhondson knows that you fixed it.