What the Hell..?

You were relaxing at the edge of a river, taking in the fresh air. You needed a break from daily life's stress, and you usually came here for comfort and peace of mind. However, today was a little... Different.

You saw a person floating down the river, upside-down with their head underwater. Small air bubbles floated to the surface, with less and less over time.

Now, naturally, you wanted to not let them drown. And why shouldn't you, considering you knew how to swim- right?