Question How to deal with fog in an indoor/outdoor scene?

Hello everyone,

I have a scene, which includes long, straight tunnels (so, we are indoor) but also big open areas, where the sky is seeable above.

Currently, I have a fog enabled and the fog color is a blueish tone which fits the sky. This looks good when the player is in the open areas. But when the player walks into the pretty dark tunnels, it doesn't make sense at all to have this bright blue fog far away, because it looks like the fog is the end of the tunnel and you can see daylight, which it isn't.

So my goal would be, that when I look to the open area, the fog is blue. But when I look inside the tunnel, the fog should be dark.

Do you have any suggestion how I could do this? Cannot imagine, that this isn't a common problem.