Something like drowning.

First you are overcome with panic.
then your mouth shoots open to call for help
but instead it makes it all happen faster
the air in your lungs replaced with water
you kick
and claw
trying to fight your way toward the world above you
but your panic holds you back
and you're stuck in place
your lungs try to get rid of the water that now consumes them
but it's too late
you start to get tired
but you keep thrashing
only not as vigorously anymore
your mind slows
and you close your eyes
hoping for some kind of miracle
and then somehow you get it
you feel hands on you
and suddenly air hits your body
and all you can do is gulp it in greedily
between harsh coughs
because your body's suddenly remembered how good it feels
to just breathe
your body is tired
and weak
and it's a chore just to keep breathing
but you do
because it feels so much better
to have the water be replaced with air
you close your eyes
and breathe it in
because somehow you made it out alive.