I have killed Scabban. I flipped the switch in his room. I dive into his "well". But, I just keep coming up a few feet away in the pool in the other room of the asylum. I am having trouble swimming. My characters keep drowning. And I can't get out of here. Help please...

Did you dive down in the lower pool and see an underwater passage that led to the flooded tombs?

Do you know where the passage is (N, S, W, or E)? Also, how do you swim? I've pressed the 0 on the number pad, but it doesn't seem to do anything. And, in the water, when i try to go forward, my party moves backward???

Thanx for the help.

If I remember correctly the passage is in the north. You have to dive underwater by looking almost straight down (PgDn), and then move forward (arrow up). The 0 is only for jumping and climbing.
The only reason I can think of that you're moving backward is that you're being attacked by fish and they push you back. That is unless you've remapped your keyboard in the game options. Check those to make sure they haven't changed.

You've swam though the channels to get to Scabban and the Asylum area. It's just forward motion in the water. Swimming down is a little different.

I use the mouse cursor to point into the water and submerge by pressing my keyboard forward movement key. Angle your mouse curosr to dive more vertically.

In the small, square pool room under Scabban's room dive down to the bottom and you'll see a square of deeper blue which is a small shaft. Continue your dive down and spin around (quickly, since you're running out of air). You should see a round tunnel under the water. Swim into it (running or jumping don't work under water so there's no way to speed up) and continue until you run out of tunnel. Look up with your cursor and move forward to surface.

Hope this helps.