Dream last night:

There was a deep cave or spring going straight down into the ground. Filled with water. The water was pretty clear and I could see deep down in the cave when I looked down. maybe 10 meters or so. I was waiting for someone. Then when I looked into the water I could see someone deep down in the water swimming upwards. I got exited, the person was diving towards the surface and as soon as he hit the surface I grabbed him and pulled him out of the water. It was a friend of mine, I think, who had done some kind of mission in the cave. I don't know exactly what. It was free diving without equipment, and I remember a fascination for the deep water and seeing him diving through the tight cave.