Long VS infinite

Strolling on a beach one day, Blubby came across a penguin, Robert Johansson, who was doing the same. The two talked for a while, neither having seen anyone of the other's species before, and they quickly learned they were both freedivers. There was an obvious question after that: Which of them could hold their breath longer? Robert proceeded to challenge Blubby to a breath holding contest, and he agreed to it.
Robert and Blubby waded out into the water, with Robert soon starting to swim while Blubby continued to just walk, even as the water began to overtake his head. "Don't mind me", Blubby said as he tilted his head back to keep breathing. "Can't swim."
"...You're a freediver that can't swim?"
"Yep, but I'm good enough at holding my breath that I don't really need to. By the way, don't get a deep breath until I've gotten mine, I take a while."
Soon, all that Blubby could keep above the surface was his nostrils, and he and Robert knew this was the place to start. Blubby's nostrils flared, and a torrent of air began surging into them as his internally-enormous lungs started filling. It took a shockingly long time, with Robert growing more and more awestruck at the sight, before the inhalation finally ended and Blubby's nostrils dipped below the water.
No other air-breather would be able to compete with the dragon like this, but Robert knew exactly what to do, miming an inhalation before diving underwater and actually inhaling. The warm water filled his lungs, but he was used to the feeling by now, and not only did it not even slightly hurt, there was an oddity of some sort with his respiratory system that made him capable of getting oxygen from water, as if he were a fish! He couldn't let Blubby know that, though, and puffed his cheeks with the mouthful of air he still had, giving the impression he was holding his breath.
After going a bit deeper, to the point that Blubby would have to backtrack to breathe, the two divers settled onto the seabed, with Robert sitting and Blubby laying down as to not tower over him. Both of them had the same thought: I kind of feel bad about not telling him... I'll do it after. They relaxed as best as they could, and the one-sided contest had begun.
Blubby was used to breath holding contests he was involved with taking a long time, but this was taking far longer than he expected. Even after a full hour had passed, Robert showed no strain whatsoever! Wow... Is this normal for penguins? Maybe I could learn something from them... Surely he was just putting on a calm front, though, it couldn't be much longer.
But it was. Another four and a half hours passed, and still, Robert had no sign he needed air. Blubby, however, certainly did; he squirmed in place, pupils shrunken and purple-tinted cheeks noticeably bigger than earlier, even the bubbles trickling from his nostrils having increased in size. H-he has it too, doesn't he? Or do penguins just have gills!?
Something wasn't adding up. Even a whale he'd met some time ago had admitted that their breath hold paled in comparison to his! Blubby did his best to ignore his burning lungs and look Robert over. Calm expression with closed eyes, puffed cheeks, not a single bubble... A rising and falling chest?
His expression soured as he realized the truth: Robert had somehow been breathing the water this whole time. Blubby got up and stormed over to the penguin, grabbing one of their flippers in his mouth and starting to drag them back to the surface. Robert yelped in surprise, the air he'd held in his mouth this whole time quickly bubbling away, but he didn't struggle. He knew exactly what this meant.
Blubby exhaled with incredible force as he surfaced, purging the immense amount of stale air from his lungs. Tossing Robert in front of him, he took some time to catch his breath as water poured from Robert's beak. After recovering, Blubby glared at him. "Were you breathing that whole time!?"
Robert blushed in embarrassment at being found out. "Y-yes..." He awkwardly rubbed a flipper on the back of his head. "I'm sorry... I should have told you I could do that."
Blubby sighed and started to calm down. "I suppose I should tell you, as well. My lungs are bigger on the inside, that's how I lasted so long."
"Oh, I just assumed that was average for dragons!" Robert laughed.
"Nope, it's just me. It's been a long time since I had to push myself like that, too."
"You find anything good on the seabed with a breath hold like that?"
"All sorts of stuff! I was actually about to head to one of my favorite places before I met you, want me to lead you there?"
"Sure!"
The two went back into the water, and with another huge breath from Blubby, they submerged once again.