Visable Underwater

do you have a skybox that surrounds the entire level - it looks like when the view is changing you are seeing the sky through the hole?

if so try making the skybox into an upside down U something like |-| to cover the level and seal off the "secret room" with other world geometry

edit - mspaint to the rescue

water can only have ONE face to it.

so if you apply water to one side, you can not have water on any other side of a 6 sided brush.

I take it the second entrance is lower than the first.

This will not work. Contiguous expensive water can only have one horizontal level.

This will not work. Contiguous expensive water can only have one horizontal level.

Click to expand...

This has to do with water levels in the Potentialy Visibility Set

In short, you can have multiple water levels in your map, just not in view of one another.
I would also recommend against carving in this case, your water brush can certainly overlap other brushes and this is often necessary when trying to fit water in complex areas. Just be sure to seal it in with nodraw brushes along the outside.

Lastly, do you have any leaks? The effects depicted in your screenshots look like they might have to do with a leaked map. Water won't look right until your map has no holes.

Ze Inspector said:

This has to do with water levels in the Potentialy Visibility Set

In short, you can have multiple water levels in your map, just not in view of one another.

Click to expand...

Correct. Just trying to KIS to avoid confusion.

I had a problem like this once, it was as simple as the water brush not being deep enough.

Looked exactly the same.