He should have had the bends and died very shortly thereafter.
The air in the sub is basically at atmospheric pressure so there isn't excessive nitrogen in the blood. The US Navy used to put submariners through a 30m ascent every four years for training. They trained to exhale throughout the ascent ("ho ho ho") to prevent lung damage.
In my era it was only once, in Sub School, using Steinke hoods. My dad did it in 1960 bare-faced, with a nose clip and a Mae West, they being in the period between the Momsen lung and the Steinke. We were loaded in "nuts-to-butts" in the chamber, a smelly, round cylinder. Access clanged shut, really loud. One peanut light bulb up in the corner. All students plus one corpsman. Arms trapped at your sides when they started letting warm water in around your feet, and it rose up your torso, giving ample time to think about where you were. This was done on purpose to test for claustrophobia. Water rose steadily until it was just below my Adam's apple (I'm 6 ft. 3. One guy I know we had to hold up by his bent elbows.) Standing in the dark, immobile, with water rising in a sealed chamber will make anyone who shouldn't go subs freak out. (This was the same day we'd already been through the pressure tank and experienced nitrogen narcosis. And snow when they rapidly decompressed when one guy blew a drum.) Once the water was stable they put about two atmospheres of air on top and opened the door to the tank. I remember looking down between my legs and seeing the female safety diver floating there, a foot away out in the tank. Steinke hood goes on over the head, pressure in the vest, squat, side-step out into the tank, and up you go.
We were trained to YELL "Ho ho ho" all the way up. It wasn't a choice. That air wanted out and it just kept coming and coming and coming . . . If the divers didn't hear "Ho" they grabbed the student by whatever they could reach and shoved them into a half-sphere plexiglass hood mounted on the tank wall every few yards to calm down. That didn't happen with my group, but one guy did refuse to exit the chamber. That female diver reached in and grabbed him by the jewels and hauled him out into the tank. He came to the surface while I was waiting to get on the exit stairs, sputtering and cursing a blue streak. I guess it was close enough to "Ho-ho" to get the job done.