Final boat ride

Out on the ocean, about a mile from shore, a small boat carried 2 anthropomorphic brachiosaurs; Shorty, a green one, and Rhett, a greenish-brown one. Both were quite overweight, and wore nothing, their flabby bellies hanging down to the point that they partially obscured their dicks. Essentially the only other thing they had in common was their hate for each other; neither really knew why, but they absolutely despised each other, and had tried to kill the other at least once. Today was going to be the last day they had to put up with each other, and not because they would make up, but because only one of them was going to be coming back.
In one of the very few times they'd agreed on something, the two dinos had come out here to attempt to push each other off the boat and into the water. With their fat weighing them down and neither having any idea of how to swim, whoever fell in wouldn't be coming back up. Of course, each thought that they would be the one to win, and despite the danger of being out in open water and unable to swim, they hardly hesitated in coming out here.
Finally satisfied with their distance from the shore, Rhett stopped the engine and turned to Shorty. "Alright, fucker, let's rock." Shorty, having been sitting down, started to get up. "Took you long enough, fuck's sa-" Rhett rushed him in an attempted surprise attack, tackling Shorty against the side of the boat! Shorty managed to push him away long enough that he could stand up, and their last fight had started.
For about a minute, the two dinos would punch and shove each other, each having several times that it seemed like they were about to fall, but managing to recover from each one. Eventually, Shorty had fallen again, and as Rhett quickly moved in to grab him, Shorty grabbed Rhett and used his own momentum to throw him above their head... And off the boat! Rhett gasped and flailed, just barely able to grab the edge of the boat, much of him now underwater. Before he could pull himself up, Shorty leaned over to look at him, and grinned. "Finally. Burn in Hell, you shithead!" With a punch to each of Rhett's hands, he was forced to let go, gasping again as he sank below the surface. Shorty continued looking down into the water as Rhett sank out of view, eagerly awaiting when the bubbles would finally stop.
Rhett thrashed as he sank, puffing his cheeks as bubbles seeped from his lips. Deeper and deeper he went, until he landed on the seabed, nearly 200 feet down. He frantically looked around for anything that might help, but he'd landed in a fairly barren area, just rocks and a couple bits of seaweed nearby. Shaking his head, Rhett tried to compose himself; he could still get out of this, he had plenty of time. Not only that, he'd actually lied to Shorty about not being able to swim; he technically could, but he was terrible at it, and with how heavy he was, he needed to have mostly-full lungs to even do it at all. While he wasn't completely full on air, as he jumped off the bottom, it seemed that what he had would be enough, and he made very slow progress toward the distant surface. He really wished he could go faster, but without any other options, he kept going as he was, trying his best to hold in his air.
For several minutes, Rhett continued his pathetic swimming, his belly and cock flopping about as he did. All the exertion was using up his oxygen much faster than normal, and he started to blush from the strain of holding his breath. At the same time, said strain was also getting him aroused, but he ignored it for now, as he was still only about halfway up. After a couple more minutes, even as he neared the surface as his blush turned purple, Rhett couldn't resist briefly jacking off. Now only able to use one hand for swimming, he started to sink back down, going about a third of the way back to the bottom before he realized it was happening. With even less time to reach the surface, he stopped masturbating and fully focused on swimming again, cheeks now beginning to get bigger.
Just 10 feet underwater, Rhett's blush was turning blue and every few seconds he'd spurt out bubbles, further slowing his already glacial progress. His lungs burned, and so did his muscles, now needing to force himself to keep going. Being so breathless was actually progressing him toward an orgasm all on its own, and his heavily-throbbing cock was starting to be difficult to ignore. Still, he kept swimming, getting closer and closer to the air he so badly needed...

Shorty lay on the bottom of the boat, having come down from his excitement and started to get a bit bored. Rhett's bubbles somehow still hadn't stopped, and Shorty was considering just leaving. It wasn't as if Rhett would be surfacing, anyway...
"HHUUUU!" A desperate gasp rang out, and Shorty bolted upright, the boat rocking as a pair of hands grabbed an edge! Looking over it, Shorty saw that Rhett had indeed surfaced somehow, panting heavily with a purplish-blue blush. "Oh, fuck off!" He then lost his balance and fell on his butt as Rhett continued rocking the boat.
"Y-you're, huuu, c-coming with me!", Rhett yelled, partly interrupted as his panting continued. The boat rocked harder even as Shorty tried to stabilize it, and before too long, it was enough to throw him out of it! Shorty splashed into the water and sank like a rock, and Rhett quickly followed, being far too tired to pull himself onto the boat or swim any more, not even having enough air in him to do so if he weren't exhausted.
Both dinos did their best to swim, Shorty's attempts being more like flailing and Rhett's being slow enough from his exhaustion that it was hardly even slowing him down. Soon landing on the seabed, they both hopped up and down as they continued trying to swim. With so little air in him this time, Rhett's blush had already gone back to blue, and his chest heaved back and forth as he tried to rebreathe in his cheeks. He looked at Shorty and gave a strained grin. "Abl-ablt leblast... Ybl-yoblu'll drblown tbl...toblo...HUU-GLP!" A moment after his taunt, Rhett was forced to suck in, barely managing to interrupt his gasp with a swallow. Shorty watched Rhett continue gulping water, their belly slowly expanding, until his drinking wasn't enough any more.
"ULP, GLUG, GLK-HUUUUGHKGL!" With just one mistimed gulp, the water Rhett kept taking in ended up in his lungs, and he immediately coughed up what was left of his air before gasping again. He doubled over as much as his inflated belly would let him, grabbing his neck with both hands as he choked on seawater. Just seconds into his drowning, his cock started throbbing even harder, cum spurting out into the water in a hands-free orgasm.
Shorty had seen enough, and was satisfied that Rhett had no chance of survival. Leaving the drowning and cumming dino behind, he walked along the seabed in search of anything helpful, as it wasn't as if he'd be able to simply walk all the way back to the shore. There didn't seem to be much to see, and Shorty slowly got more and more nervous as his need for air slowly grew. Just like Rhett had, he started getting hard from holding his breath, but hardly even noticed, focused on at least finding air if not a way to the surface.
Quite a while passed to no avail. Shorty was starting to strain and blush, and he blew a few bubbles to try to help, which it didn't. Admittedly, he was growing to like being down here, and had he been able to breathe, he'd likely be enjoying himself. As it was, he didn't want to be here another second!
After nearly 13 minutes underwater, his chest started to heave and his cock started to throb. Shorty still ignored his arousal, and soon came across a strange sight. It was Rhett! He was laying on the ground, his whole body tinted blue and his belly even bigger than it had been when Shorty last saw him. Rhett was clearly very drowned, but somehow still alive, weakly gurgling and occasionally hiccupping. He seemed to briefly react when he saw Shorty, and tried to say something, but couldn't. Not long after that, he shuddered and his eyelids slid shut, his twitching stopping a few seconds later. Shorty was definitely happy to have seen his rival's last moments, but that didn't exactly help him breathe, so he moved on.
20 minutes in, Shorty was starting to run out of breath. He rebreathed in his purple-tinted cheeks that would repeatedly grow to half the size of his head, and he was finally jacking off in an attempt to distract himself from his burning lungs, which did help at least a little. Eventually, he happened across a cave, and while he couldn't see very far into it, there seemed to be a small air pocket near the entrance! While it was too high up for him to be able to reach it, there were some large rocks nearby, and he spent a minute to roll them about so he could use them as an improvised staircase. After that was finally done, he climbed up, eager to finally get a breath.
"HUUUU, HU-KAKH! COUGH, HACK!" It wasn't air, but some kind of gas! After a brief bit of choking, Shorty forced himself to gasp and hold his breath again, recovering some of the stale air he'd exhaled, before sinking back underwater. That gasp had of course gotten some of the gas with it, and his lungs were burning even more than before. He masturbated again, and while it didn't really help this time, he kept at it anyway.
In just another minute, Shorty was about ready to give up. With a blue blush and repeated coughing into his head-sized cheeks, he struggled on, covering his mouth and continuing to jack off. He considered just exhaling so he could get the gas out of him, but he knew what would follow that. His body, however, soon made the decision for him. Shorty stopped in place, shivering with wide eyes, both hands on his mouth as bubbles spurted out regardless. With all the masturbating he'd done, being moments away from drowning was enough to push him over the edge, and as his cock started shooting out cum...
"GLK! MMBLABALABLABL-HUUUAAAGHK!" Shorty finally couldn't hold his breath any more, and while it was a relief to get the gas and useless air out of him, what replaced them wasn't any better. His orgasm intensified as he gasped seawater, loudly gurgling with each throb of his cock. After a few more seconds, his orgasm ended, and the last few bubbles were coughed out, the dino's lungs now only containing water. Shaking his head, he tried to run, the growing dizziness making it hard to do, but he managed a sort of awkward jog. Surely there was something around that could help?
Choking and hiccupping, he scrambled around on the seabed, but it was still pointless. After several more minutes of drowning, the pain finally started to fade, and in one more minute it was gone. Shorty was starting to go numb, simply panting water at this point, and was starting to occasionally need to remind himself of what he was looking for. As the growing lack of oxygen dulled his mind, it slowly took longer and longer to remember. His aquatic breathing calmed further, now pretty much normal aside from the fact that he wasn't breathing air.
With another hiccup, Shorty happened to notice that his gut was bigger than he remembered, apparently filling with some of the water he took in. Paying it no mind, he blearily looked around, finding another cave. It had some kind of wide glistening thing on its ceiling near the entrance, but it didn't seem important. He was looking for air, not... Whatever this shiny thing was. Deciding to just leave it alone, he moved on.
Shuddering and gulping, his vision started to blur, his body tinting blue. It was certainly be impressive that he was still moving at this point, and while was clear he wouldn't be able to hang on all that much longer, Shorty himself didn't realize that. As he wandered about, it occurred to him that he'd gotten hard again, though he couldn't tell why.
Now having been drowning for 12 minutes, the flooded dino still knew he was looking for something, but had entirely forgotten what it was. Surely it wasn't that important, otherwise he would've remembered it. For now, he would take a break from searching, and take care of himself. Sitting down, which he hardly even felt, Shorty reached around his bloated gut to start weakly jacking off again. His lidded eyes partly rolled back and his tongue hung from his mouth, now only taking shallow breaths as his consciousness started to fade.
"...nnguuurrhhh..." He groaned in pleasure, his waterlogged voice barely audible, before holding his breath. With his cheeks a bit bigger than his head, he hiccupped a few times, then exhaled and resumed his useless breathing. Each breath further inflated his belly just a little at a time, and while it was eventually too big for him to reach his cock, he didn't notice, still believing he was masturbating.
2 more minutes, with Shorty starting to briefly lose consciousness every few seconds, it turned out that believing he was masturbating was enough in this case. His eyes rolled back again, and with a few weak throbs, a pretty small amount of cum was spurted just past his oversized belly. In his delirious state, he hallucinated much more being shot out, nearly triple what his previous orgasm had.
Feeling incredibly tired, the thoroughly-drowned dino allowed himself to fall backward, blearily staring up at the distant surface. Something about it was gnawing at him, but he couldn't figure out what it was. Maybe it was what he'd been looking for? Well, he'd found it, so, mission accomplished. He was exhausted, though, and his dim vision made him believe it was night, so he decided to sleep before anything else.
"...hic.......HULP, GLUK!" Shorty finally remembered what was happening; he was drowning! As his body burned through the very last of its oxygen, he scrambled to his feet and tried again to swim, hopping up and down and clawing at the water, huge belly flopping about. Just like earlier, it was pointless, and already his energy was fading, his struggles quickly slowing down until they appeared half-hearted, as if he didn't even want to surface. Dropping to his knees, he fell forward to lean on his belly, hands still weakly paddling for a brief time until his arms went limp at his sides. Shivering, his mind went blank, and with just a few more seconds and one last hiccup, he passed out, his blue body doomed to kneel on the seabed for who knows how long.