Board Thread:The Lumber Tavern/@comment-1178822-20160113071737/@comment-26143979-20160113163248

Yup -- the entrances being:

The Spawn Area Sinkage, a terrestrial way of going into the biome

The Swamp Rock, a hole that the player drops down into the caverns below.

The River Tunnel, a way for Boats to enter the underground biome.

There is more than enough proof for this, but i can't explain it all right now