Pier Pressure (map name: sy_1)

Either way, you'll score yet another key, this time the shipyard key (you guessed, it, the cheat code here is give shipyard_key). The room with the vent hanging open in the ceiling poses another nifty little puzzle. Just jump on the crates (run up the ones leaning against the wall, then jump over to the big crate), then jump and run up the vent. It doesn't look like it will work, but it will. Past another vent climb, you'll find a fork in the vent. Straight goes to a vent facing down, which leads to the roof, and a nasty drop to either side. Left in the vent leads to the storage room with the armor on the shelf that's too high to reach from the ground.

Once you have the shipyard key, go to the big boat (not the little dingy) and kill everyone. Only when everyone is dead will the magical door to the boat open (not the one marked "security" -- it never opens -- the other one). This includes the thugs up on the railings, and the ones hiding behind the crates, and -- well, just kill everyone!. Some people have reported that the door does not open, even after they are sure everyone is long deceased. If this happens to you, just use the noclip cheat to walk through the door and into the next level!

Das Boot (map name: sy_2)

...but the door is rusted shut. Make sure you pick up the copper colored oil can from one of the storage rooms (on a shelf to the left), or use the cheat give oil can, then activating the Engine Room door will play a little oil can sound and open it right up.

Keep working your way in, killing the thugs and bitches and dropping down below the catwalk (and going back up again) as necessary. It's linear, so you can't miss if you just keep moving the same direction. Though it's sometimes hard to tell a "boss" in Kingpin, you'll know this guy when you pop three rockets on his forehead and he runs off. Keep at it, there's no magic required to take him down, but it does take a lot of ammo.

Backtrack to reload, heal, and get new armor as necessary. He will follow, so don't get careless.