Before we begin:
-Turn on the Power
-Open up the doors until you get to the room with PhD Flopper.
-Be sure someone gets the VR-11 before it is required (Step 8).
STEP 1:
You need to locate the door in the lower part of the room with PhD Flopper. Have anyone stand in front of it, and you will hear someone knocking and calling from the other side of the door. You will be given the first task of finding a fuse to fix the lights in their room. The fuse is upstairs, where PhD Flopper is, look on top of both desks and inside of the cabinets. You need to hold 'X' for all interactions (picking it up and placing it). Return to the door and place it inside the panel on the right.
STEP 2:
More dialogue and you will be tasked to search and destroy four security systems. To destroy them, you need to use explosives. I have only tested Frags, Semtex, and the Scavenger, but I'd assume other explosives to work as well. You need to be sure that the explosions hit the glowing red spot. If you are off at all, it will not turn off. The first mechanism is behind you, where the door is. The second mechanism is behind Stamin-Up. The third mechanism is along the bridge extending from the base of the Lighthouse, where the AK-74u is, towards the broken ship. The fourth mechanism is off the left of the ship, where Claymores and Double Tap are located (it's to the right when you first go onto the ship). You do not need to do these in order. Return to the door when done.
STEP 3 (Co-Op Only):
Vodka, you must find the vodka! This requires cooperation. First, the vodka will spawn frozen, inside of ice, hanging on a ledge above another walkable area. It may appear on a railing, the bottom of a staircase, or the bottom of a leap down. To our knowledge, it only appears outside, on top of the PhD Flopper room, or on the power switch half of the ship. To obtain it, one person on top must knife the ice while another person is on a walkway below to catch the ice. The person who catches it needs to put it in the tube on the left side of the door. If you miss, the Vodka will spawn again in another part of the map..
STEP 4 (Co-Op Only):
You need to locate four Radios. Underneath the power room, where the box sometimes spawns, the first radio is on top of some equipment. In a corner of the Stamin-Up room, on top of some barrels is the second radio. The third radio is inside of some shipping containers on the right half of the back end of the ship, near where the zip line from the Lighthouse ends. The fourth radio is next to the door, look on top the cabinet under the staircase. You must hit them in order and within seconds of each other to activate the Morse Code light in the sky.
STEP 5:
Now that the light is beeping out Morse Code instructions, you need to make your way to where the power switch is. Opposite of the power switch is a wheel and two levers you can interact with. Turn the wheel right twice, pull the left lever once and the right lever three times.
STEP 6 (Co-Op Only):
At this time, you need to set the code in the lighthouse. The code from top to bottom is 2746. Whenever you turn any of the dials, the dials on the floors above and below turn in the same direction. If you would like my method of doing this: Turn the top one to 2. Now look at the floor below. Count the number of turns you need to get to 7. Go down another floor and turn that dial the number of turns needed to get the above one to 7. Now set the bottom one to 6. Go up one floor and count the number of turns it needs to be 4. Go up to the one set at 7 and turn it that many times. Now go to the top floor and set it to 2 and all numbers should be correct.