Dream About Swimming In A Lake At Night

I am swimming in a large lake with lots of people at night in the dark. We are all delighting in it, talking to each other and laughing. It's time to get out of the lake, and we are swimming to shore. I come out of the water, walking on the wet sandy shore. I am then in a large building with a few friends. It's like a large school building in the middle of the night. There is a presence that we feel is quite negative we talk about and anticipate amongst each other, but never is seen or revealed. There are several female employees in the building that we run into and to whom we try to explain our anticipatory dread.