The ice cold water hit him hard, knocking the wind right out of him and for a moment Dean lost his focus; his head felt like it was going to explode and his body was screaming at him to get out of the water, to get warm but Dean ignored it. He wasn't going without Sam.
Dean wasn't in the water for long when he saw the car, it had been completely consumed by the water but had not yet sunk to the bottom. Dean was praying and hoping this meant Sam had been able to find an air pocket or got himself out of the car by now. His baby brother was strong but God, the water was so cold! It was enough to send anyone's body into shock.
"Sam!" Dean tried to call out in the water but instead just got a mouth full of dirty, salt water.
Reaching the car, Dean tried the door handles to no success. He had spotted the deceased driver by now but he still couldn't find Sam. Dean didn't know how long he could keep this up for, he couldn't concentrate on anything but getting to the surface, for air at least. His mind however, managed to focus enough on the limp body in the back seat of the car for Dean to take control of his body.
Kicking the whole force of his body into the car door, Dean managed to unstick it enough to pull Sam out and just in time in fact. Because, boy, was Dean cold. He could no longer feel his hands or feet and the rest of his body felt like he had pins and needles in it, but Dean's main focus was on Sam who 's skin looked a freaky blue colour.
Breaking the surface, Dean kept Sam's body afloat whilst gulping in deep breaths of much needed air. "Sam!" He called out to the limp body in his arms. No reply.
Dean couldn't pull himself and Sam to the edge of the riverbank. Hell, he barely had enough energy to keep both him and Sam's heads above the water but he knew if they didn't get out soon they were both going to inevitably get hypothermia or pneumonia but Dean was tiring and he was exhausted. His vision was fading quickly and before he realised or had time to do anything about it, his body had submerged once again into the murky waters, taking Sam down with him.