MAP04: Dirty Water (BTSX-E2)


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This level occupies the map slot MAP04. For other maps which occupy this slot, see Category:MAP04.

MAP04: Dirty Water is the fourth map of the second episode of Back to Saturn X. It was designed by Mike Alfredson (Use3D) and Richard Frei (Tarnsman), and uses the music track "Lost City" by Sarah Mancuso (esselfortium). In the official add-on version, this level's name is Sunken Sanctuary.


Map of Dirty Water
Letters in italics refer to marked spots on the map. Sector, thing, and linedef numbers in boldface are secrets which count toward the end-of-level tally.



To get the keys you must locate four colored crucifix buttons - two per key - that will raise bridges leading to the necessary teleporters.

Walk straight forward to get a plasma gun, noting an arachnotron to your left, then enter the torch-lit building straight ahead to confront a mancubus (plus two overhead revenants on Ultra-Violence (UV) and Nightmare (NM) skill levels). Push past the mancubus and head down the steps to a door, open it then head straight forward to a junction and turn right to see a Hell knight (or two more revenants on UV and NM) blocking your path to a yellow crucifix button - this is the first button needed to reach the yellow key. Kill or avoid a baron of Hell (or arch-vile on Hurt Me Plenty (HMP) or higher) that is hiding in an alcove to your left, then head back to the starting point and run south until you go down some steps to a shotgun. Continue south to a hallway with two doors and pass through the door to your left, drop down to an enclosure with some waiting imps (plus knights on UV and NM). Go up the steps and turn right to see a door ahead; approach it but do not open it immediately, as a mancubus is waiting behind it and demons will appear behind you to cut off an escape. Push past the mancubus and go up and down two more sets of steps, then drop into the ditch ahead and turn right to find some imps guarding a door. Open the door and go straight forward to a blue crucifix button - this is the first button needed to reach the blue key.

Kill the knight (or mancubus on HMP or higher) that teleports in then go back to the ditch and press a button directly ahead to open two doors to your right, which lead back to the throne room. Go through and turn left to find the second button needed for the yellow key, then drop into the water below and push a second button under the window to lower a lift next to the bridge you just raised. Go up to the bridge and cross it, then look behind the stone throne to find a switch that will lower a lift in the east wall. Ride that lift up and drop into the water pool ahead (imps and revenants will teleport in if you make any noise here), which will lower all of the small platforms inside it, then take the megaarmor and look in the south-east corner for another switch that will raise the platforms again. Use the lift in the opposite corner to get back to the floor above then carefully step across the platforms to reach a candle-lit doorway in the south wall; through it are some imps and a baron/arch-vile guarding a teleporter. Enter the teleporter and step forward into a water pool with some arachnotrons (and mancubi on HMP or higher), then enter the building in the middle of the pool to find the yellow skull key.

From the yellow key, go back to the entrance teleporter and step through it, then look left to see that a door has opened to reveal a fire wall. Step into the fire to teleport to a chamber on the east side of the map - which you will need to revisit once you have both keys - then step onto the bridge in front of you before stepping back into the teleporter to return to the torch-lit building near the starting point (if you do not step onto the bridge, then you will get stuck as soon as you re-enter the teleporter). Head south to where you found the shotgun and continue on to the hallway with two doors, then open the right-hand door this time to reach a heavily-guarded path over water. Follow the path until it turns to the east, then look right to see a lift ahead with a switch next to it. Pull the switch and ride the lift up, kill a couple of waiting imps then turn left and push past one or more revenants to find the second blue button.

Ride the lift back down, passing one or two more revenants on the way, then head due east towards a building that has a large blue skull on it. Head around the south side of the building to find a tunnel with some blue torches and open the door at the end, then go round the corner to confront one or two mancubi as well as knights/revenants (the entrance will seal behind you). Open another door to the west and head across a bridge to find a large blue switch that you can pull. Step off the north side of the bridge and enter a doorway on your right flanked by blue torches, then go down some steps and turn right to step on a lift that will carry you up to the floor above. Go round the corner and dispose of some imps and demons, then head into the next room and step on the center teleporter to go to an outdoor section with arachnotrons (or mancubi and a spiderdemon on HMP or higher). Go inside the center building to collect the blue skull key.


From the blue key, go back to the entrance teleporter and step through it, then look left to see that another door has opened revealing the fire-wall you stepped into earlier. Enter that wall again and cross the L-shaped bridge in front of you to reach dry land, then open both locked doors to the north and pull the switches behind them to raise two more bridges from the lava, turning the L into a crucifix. Head to the south point of the crucifix and step over the wall that lowers ahead to reach another bridge and follow it east until you reach a mancubus (or three revenants on UV and NM), then head north past another wall that lowers as you approach to reveal imps and more revenants. Enter the dark room ahead and turn left to dispose of one or two knights, then press the button in the north alcove to lower a lift that has another knight on it (there will also be a cacodemon on HMP, or a pain elemental on UV and NM). Ride the lift up and follow the path north to some steps, kill two revenants (or an arch-vile on UV and NM) that are waiting ahead), then enter the teleporter straight ahead to land on a platform where one or two mancubi are guarding the exit teleporter.

Other points of interest[edit]



  1. From the start, enter the torch-lit building straight ahead to see a mancubus in front of a green slab with a spine texture. Shoot this slab to open a second wall to the north, hiding a chaingun, two boxes of bullets and three stimpacks. (sector 52)
  2. At the very southwest of the map, ride the lift into the building with a blue switch inside. When you approach the blue button, a monster closet containing one or two revenants will open behind you. The back wall of this closet is made of one large slab rather than several smaller ones; opening it will reveal a teleporter, leading to a small room in the far east with a supercharge. (sector 1001)


  • After using the yellow and blue keys, head right facing them onto the now raised walkway. Go up to the dark door and it will lower, revealing a mancubus and a teleporter to the left of it. Take the teleporter to go back to the beginning into a closed section to grab one energy cell pack, two stimpacks and 10 armor bonuses.


The fire wall between the teleporters that go to the key building will send you to a teleporter near the locked doors. If you step off this teleporter then immediately step back on it, you will teleport to the torch-lit building near the start but will not be able to move as the teleporter pad is stuck against the ceiling. That pad will only lower when you step on to the L-shaped bridge near the locked doors; you will cross a walkover line that makes the pad lower to the floor.

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Current records[edit]

The records for the map at the Doom Speed Demo Archive are:

Run Time Player Date File Notes
UV speed
NM speed
UV max
NM 100S
UV -fast
UV -respawn
UV Tyson
UV pacifist

The (absence of) data was last verified in its entirety on February 21, 2022.


Map data[edit]

Things 1042
Vertices 5617*
Linedefs 6494
Sidedefs 8975
Sectors 1086
* The vertex count without the effect of node building is 5172.


This level contains the following numbers of things per skill level:

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