A Dangerous Dip

Despite it being late at night, well past closing, the indoor pool's lights were on. It wasn't that someone had forgotten to turn them off, but someone else had turned them on. Someone who shouldn't have been there. While they wouldn't currently be visible, the bubbles surfacing next to the deep end's ladder would certainly give them away.
Below the surface, the pool's sole occupant could be seen: A chubby, blue tyrannosaur with a pale-blue front, one hand holding the bottom of the ladder as the other stroked his dick, cheeks puffed as he held his breath. His name was Chomper, and while he couldn't swim, he still loved being underwater. It always got him incredibly horny, especially being in a precarious position like this, one lost grip away from disaster.
"Mmn...Mf..."
Soon enough, he was starting to run out of breath, having been holding it about two minutes now. Still, he stayed where he was, jerking off a few feet from the surface as his belly started to subtly twitch from his growing need for air. Eventually, despite how much he enjoyed this, Chomper couldn't really handle the breathless feeling any more. He pulled himself up a bit, grabbed the ladder with his other hand, and quickly climbed out.
"Pah, huaahh!"
His gasp echoed around the room, and surely would have alerted anyone there to his presence if he weren't alone. Just as well, since he was... You know, trespassing. He leaned against a handrail as he caught his breath... Hm... Those bolts aren't looking so hot... The bolts holding the ladder in place were pretty heavily rusted. Clearly whoever owned the place didn't care too much about maintenance. Beggars can't be choosers, I guess. I'm sure it can handle a while longer.
Chomper climbed down a bit so just his head was above the water, and took some deep breaths to get his lungs ready.
"Huff, huff, huff, huuuup!"
Back underwater he went, heading to the bottom of the ladder and hanging from it once again, resuming his pleasure.
Nothing that significant happened for a while, some bubbles floating from Chomper's nostrils as he simply masturbated. Again, though, a little more than two minutes in, his lungs started to complain.
"Hmb...blblblb"
He blew some bubbles to relieve some of the pressure in his lungs for a while. He was going to push himself this time, and only surface once he really needed to. His belly started twitching again, pushing out little grunts as he puffed his cheeks a bit bigger, about the size of softballs.
Three minutes, now. Starting to blush from arousal and strain, Chomper decided to change his strategy a bit, grabbing onto the ladder with both hands and simply focusing on holding his breath, facing away from the wall. This far down, and so low on breath, his arousal was slowly building up on its own. He'd always wanted to have a hands-free orgasm, and while he wasn't sure just breathholding could make that happen, he still wanted to try. Bubbles were more often slipping free of his lungs, now, and his belly was heaving in and out, but he wasn't going to give up on his goal just yet.
Three and a half minutes. Chomper was letting out little whines, now, and his cheeks had become as big as grapefruits. He started to consider giving up, and going to get air... But, no. This time, he would go as far as it took. His pleasure continued to build, dick throbbing as he couldn't help but thrust his hips forward a few times.
"Mm! Hm-mmm!"
Four minutes without a breath... He couldn't take it any more! Chomper could feel an orgasm building up, but with his blush beginning to turn purple and his belly convulsing, he was too afraid of drowning to continue. Spurting out some bubbles and pre, he scrambled to start climbing back up again, knocking the ladder around a bit-
SHREEE-KLANG!
"ABLABLH!" The ladder shook and tilted to an awkward angle, nearly tossing Chomper off it! That could've only been one thing... Shit, one of the bolts just broke! He continued frantically climbing, he needed to get out before the other-
KLANG!
"NOBLOBLO!" The other bolt broke, and the ladder started sinking! He pushed off of it, jumping towards the surface and flailing his arms... Just barely missing the ledge, then sinking like a rock! But, now that he was in real danger of drowning, his arousal surged, and he finally had the hands-free orgasm he'd wanted, leaving a trail of cum as he sank and flailed about.
Reaching the bottom and landing on his back as he came down from his orgasm, Chomper fully realized what he'd just gotten himself into. For whatever reason, the pool didn't have a shallow end! What the fuck kind of pool doesn't have a shallow end!? Already so oxygen-deprived from the past four minutes of breathholding, with a purple blush and volleyball-sized cheeks, he had to figure something out quick!
With his hands over his mouth, he glanced around the pool's bottom. There was... Nothing he could use. Just an ordinary drain, and the broken ladder that had sent him down here. Maybe I could lean the ladder against a wall? Chomper grabbed the ladder, and with a lot of effort, managed to start tilting it upward. It was a good thing the water was somewhat reducing its weight, it would have been too heavy for him to lift otherwise.
Having propped up the ladder on a wall, he grabbed onto it and carefully started climbing. Eventually, Chomper reached the top of it, though was still some distance from the surface... But, not enough that it was hopeless! He jumped up from the top step, causing the ladder to wobble a bit, and got just a few inches from being able to touch the surface with his fingers. Another jump shook the ladder again as he got slightly higher, then a third jump knocked the ladder loose, sending it sliding down the wall and laying flat again!
Chomper landed next to the ladder. Fuck's sake, this is gonna keep happening and waste so much time! Thirty seconds, he'd been stuck down there, and he was actually past his breathholding record now, though he wouldn't care even if he knew about it. Again, he set up the ladder against the wall, climbed back up, and jumped a few more times, still not accomplishing anything... Then, an idea. Maybe if I jump forward a bit, I could push down against the wall and get a little higher... He gave it a shot, immediately knocking down the ladder again as he pushed off, and sure enough, he got higher than before. High enough that he could brush his fingers against the surface! Clearly, this was the way to do it, though he'd have to set up the ladder every time.
Nearly five minutes, Chomper had been underwater. His lungs were burning so bad, he started to consider just giving up and breathing... N-no! I can do this! His belly was heaving and contracting, and his cheeks were now at this size of basketballs, but he was determined to keep the water out of him. Once again, he set up the ladder, climbed up, and jumped from the top, still not getting high enough...
A full minute passed like this. Set up ladder, climb, jump, set up ladder, climb, jump... Chomper managed to get most of a hand above the water once, and only once, so low on oxygen his strength was beginning to fade. With his blush turning blue and cheeks getting even bigger, he thought about giving up again. I...I can't do it...E-even breathing water has to be better than this... And so, six minutes in...
"HUU-GLP!"
He finally gasped, but instinctively swallowed. His mind may have given up the fight, but it seemed his lungs weren't done just yet. Again, though, Chomper sucked in.
"HU-GLP! ULP!"
Once again, he gulped the water, keeping his air-starved lungs dry. It tasted oddly okay, and even seemed to lessen his desperate urge to breathe! Still, though, it forced open his mouth again to suck up more water.
"GLP, GLP, GLP"
He was getting a slight fuzzy feeling in his head, and starting to lose his senses.
"ULP! HHULP, GLP"
Chomper was beginning to feel somewhat heavy... Looking down, it sort of looked like his belly had gotten bigger. His instincts forced more drinking, and he made sure to watch his belly.
"Glup! Glp glp!"
Sure enough, his belly was expanding from all the water his instincts were forcing him to swallow. I wonder...How big it can get... His dulling mind forgot about his desperation for air, and he now willingly chugged the water around him.
"Ulp, glp, hic-glup!"
More and more pool water poured into his slowly bloating stomach, now looking as if he'd swallowed a watermelon. His now fully blue blush was starting to spread across his face, but he didn't care any more, barely noticing the burning of his lungs as he simply continued to work at quenching his seemingly endless new thirst.
As the seventh minute hit, something weird happened...
"Glp, G-GHUUULP!"
Chomper quickly grabbed his neck before it occurred to him... He'd somehow sucked water straight into his stomach as if he'd inhaled, though his lungs were still dry! His waterlogged belly was quite inflated at this point, about two feet wide, and the added weight was making it somewhat hard to stand up with his weakening muscles, so he sat down.
All the breathholding, struggling and drinking was taking a toll on his mind, as well as making him horny again. Chomper could certainly feel his dick getting hard, though his belly had gotten too big for him to see below it. With another few gulps, he reached down and started masturbating again.
Thirty seconds passed like this, jerking off on the pool's bottom and smushing his bloated belly around as his continued swallowing expanded it even farther, his whole face now blue from the lack of oxygen. Chomper was starting to feel a bit dizzy, but also noticed a slight ache in his belly... Not once during all this had he thought about the fact that his stomach could only hold so much. Shhit...what's gonna happenn when I'm ffull? Well... That was something he could worry about later.
The moment arrived sooner than he expected, however. "Ulp...g-glup...khk!" A last couple gulps, and his belly was full, stuffed to the brim with pool water and now nearly four feet wide. Chomper gagged a bit as he tried his best to force in a little more, but it just wasn't gonna happen. His body kept involuntarily sucking in, though, and there was only one place the water could go, now.
"Ghk...Kl! G-GHUUUAAAGLKGK!"
Eight minutes underwater, with two minutes of excessive gulping of water, and Chomper finally inhaled. Already having been close to an orgasm, the shock immediately got him the rest of the way there, sending cum... Not that far, actually, with his belly being so big it totally covered his dick.
"HLK! GRLK, HUA-KHK" Chomper grabbed his neck with one hand and flailed about with the other, too heavy from all the water in his absurdly large stomach to move at this point.
"G-ghuh! Huuak!" He was rapidly weakening now, already so low on oxygen that the fact he'd held his breath so long didn't really matter any more. His belly bounced about with his convulsions as he squirmed in place, already not bothering to hold his neck any more.
"Huuah...hic...huff..." No longer having the energy to struggle, Chomper let his arms drop, landing on his oversized belly. He weakly smiled as he jiggled it a bit and his vision faded... Then, he closed his eyes, and let himself succumb to the lack of oxygen.