Dionisos

(Went to bed at 4am which is actually earlier than the days prior. I should really stop that)
(This dream was completely in english and I even used foot as a measurement even though I normally only use the metric system in real life and dont know anything about the imperial system at all)

I was inside a limestone cave with 3 other people for unknown reasons. I was standing in front of a chasm with a rope which led down about 15 meters to another cave area with a very small "lake" (the lake was about 4x4 meters I'd say and very shallow so it wasnt really a lake at all).
Above the rope there was a sign which read "Danger! Water extremely cold." which I thought made sense.
The people I was with wanted to climb down and one of them (some girl though I dont know any of the people present) wants to swim in the lake. She either climbed down really fast or jumped (which would probably kill you) because suddenly she was in the water and telling us to get in because "its great in here" which I found strange at the time. At the point where I climbed down the rope everybody is already in the water and saying its great.
I suddenly notice that the water is rising at a very quick pace (in the dream I said it already rose 2 feet in a few seconds) and shout at them to get out and back up the rope.

The water is rising even faster now with us basically beeing carried upwards to the beginning of the rope by the water.
Then I noticed something which truly shocked me, as a ceiling of water was coming down on us from atop. The water was not flushing down but rather it was as if gravity was turned around further above and the water was simply rising. After a few seconds there would be no more space to breath left and we all took a deep breath and prepared to try to swim out of the cave.

At this point I was not really a part of the 4 people anymore as I was constantly switching around viewpoints while following different people at a time while I could even hear their thoughts. Mostly they didnt think they would be able to make it out the cave and where already pretty much out of air but in the end they managed to swim up to where the exit is through the curiously bright cave system.
To get out of the cave you had to open a hatch which then led outside and in the end I was thinking what if when we open that hatch there still is even more water and it was all for nothing. What exactly happened I dont remember and the dream pretty much ended here.

(I do not have a fear of water or anything related but it was pretty horrifying because it felt like a malavolent entity with unearthly power wanted to kill us)