Smugglers' Hollow
Smugglers' Hollow is the coast's honest answer to an occupied continent: if the roads are unsafe and the ports keep records, you move goods under both. The Hollow is a working tunnel network with lookouts, shifts and a quartermaster, and it does more trade than the harbour above it. Nobody here is a monster. Everybody here has a reason to make sure you do not come back out and describe the layout.
The fights change character as you go in, which is the tell that this is a business rather than a den. The cove lookout runs. The deckhands and runners fight like men protecting a wage. Deeper down you meet enforcers and a powder-keg saboteur who are perfectly willing to bring the tunnel down on both of you, because at that depth the cargo is worth more than the crew.
Encounters
Tier 1
Cove Lookout
Tier 2
Smuggler Deckhand
Tier 3
Contraband Runner
Tier 4
Cutthroat Enforcer
Tier 5
One-Eyed Marlow (Mini-Boss)
Tier 6
Powder-Keg Saboteur
Tier 7
Tunnel Knifeman
Tier 8
Smuggler Quartermaster
Tier 9
First Mate Skarn
Tier 10
Captain Vexa Blackmoor (Final Boss)
The final boss
Captain Vexa Blackmoor never goes to sea any more and has not needed to for years. She runs the Hollow the way a shipping company is run, with First Mate Skarn as the part of the operation that does the shouting. She fights economically, without flourish, and treats the encounter as an unusually expensive delivery she intends to sign for.
Before you enter
The recommended level is 5. Treat it as a starting point: farm earlier tiers, upgrade gear, and adjust your pet when a boss stops you.
Difficulty inside a dungeon comes from one number that climbs with the tier, and the step between tiers is a large fraction of the gap between dungeons. So a wall at tier 7 here is not a signal to grind this dungeon harder - it usually means the opening tiers of the next dungeon are a better use of the hour, and you come back with the gear they dropped.