Removing blue shadows?

[Burut]

I am wondering if it is possible to remove blue shadows that appear when creating cave maps. I'm planning to create a cave adventure map, going from cave to cave, random encounters every time you start another game, and as I started creating the starting location I noticed some kind of blue shadows are appearing, and it really ruins the expirience. Tought it was only in the editor but no, it's in the game too. Gonna post the picture of what I mean.