I was on a diving board beside a lake. Although people were on the shore, nobody was swimming. I didn't know why, but I thought the water might be too cold. Finally I saw a young man beside the lake and I asked him to test the water. He walked to the water to touch it with his foot, then suddenly fell in. I realized he probably couldn't swim. I saw another man had jumped into the lake to try to save him. I also jumped into the water. I swam to the area where the man had fallen, and I dove deep below the surface. Finally I felt a hand and grabbed it. I began swimming to the surface, but now I had little air left in my lungs. I was uncertain I could reach the surface.