I'm swimming in a pool with my friend. The pool is big, there are corals at the bottom of it and there are some fish swimming around, too.
We are showing off as usual, doing all kinds of tricks underwater. "Hey, come here!", my friend calls and I dive to swim to her. I decide to do a little swirl in the way but as I do so, I lose my sense of direction and I'm not sure where the surface is anymore. I'm turning, turning and I feel my air is running out.
Then suddenly I get the surface in view and start swimming towards it. My air runs out before I get to the surface and as I gasp for more, water fills my lungs. It doesn't feel bad at all and for a second I'm thinking "wow! I'm actually breathing water!".
I can't feel there'd be anything wrong and I'm still trying to get to the surface, but I'm just getting heavier, and tired all the time.
The more water I breathe, the more tired my limbs start to get until they feel so powerless that I simply can't move at all. I start falling towards the bottom of the pool, still breathing water, looking at the surface sparkling in the light, knowing I can't reach it and that I'm going to drown.
I start to feel tired and sleepy and when I hit the bottom, I am totally unable to move anymore and close my eyes.
[I woke up gasping for air, my lungs and throat burning. I probably woke up just when I had stopped breathing.]