This is slightly more complex than regular water. This type of water utilizes a teleporter to mimic submergible water.
Submergible Water
Create an above-water sector, and a below-water sector. These two sectors must be the same size and shape. Tag the above-water sector [0,1], and tag the below-water sector [0,2]. Texture the above-water sector's floor with water (#336), and the below-water sector's ceiling with water. If you want the water to look like sewage, change its palette to 8. Place an S[Channel,7] in the exact same place in each water sector. The angles of each S have no effect on submergible water teleporters. Although it may seem like the sensible thing to do, do not raise the below-water S: Both must be "grounded" in order for the effect to work properly.
Notes:
- This type of teleporter will not impose a delay on objects attempting to pass through it in quick succession. A player's movement will not be momentarily halted after passing through this type of teleporter. The motion is continuous, which helps to suppress any suspicions of teleportation from the player.
- Don't place toilets or urinals underwater. After having a slash in the pool, you cannot resurface! I suppose that's a suitable punishment for the crime.
Submergible Slime
Contrary to popular belief, you do not have to give the underwater S a palette value of 8 (or 3, or anything) to make slime.
To make Submergible Water glow like slime, simply replace the water textures with FLOORSLIME (#200). Technically, you only need to do this to the below-water sector's ceiling, but you should also replace the above-water sector's floor texture for consistency.