Syryn's group began their swim out of Silisia. They crossed the shipwreck zone and went through a deep canyon whose walls exposed the skeletal remains of underwater creatures that had died aeons ago. The mage was shocked by the size of some of the skeletons. If the wearers of those bones were still alive, he was sure that the mermen would not be living in peace the way they were.
Up ahead of him, the mage could hear the clicks and whistles of a dolphin pod frolicking over a bed of clams. The clamshells were the same ones that the merpeople slept on. But these clams were not empty. Tightly shut shell mouths let out a few bubbles of air from between their ridged seams. It happened often enough that the water above the clamshells was filled with tiny bubbles of air rising to the surface.
So here's the mass release. I hope you enjoy it.
Also, Dolphins dont dive this deep because they only hold their breaths up to 10 minutes. But yeah, the ones in my story are special. They have a cavity inside their body that stores compressed air which they use for deep dives. I didn't want to add to chapter length with the explanation so I put it here.