"I can't! I can't," Rarity quietly screamed, wet mane flinging droplets as she shook her head. Derpy instructed her other student group to proceed to the deep end and wait on the bottom. Twilight, Fluttershy and Rainbow Dash affixed their masks and regulators then quietly dropped under the surface of the pool to glide down to the deep bottom on the other end.
Applejack and Pinkie stood near their buddy Rarity as Derpy spoke- "I know it's not normal, for ponies to breathe underwater and I too took time to get comfortable with it. But we've got to remember we can do it, OK?" Rarity nodded; "But it's hard, it brings back memories I'd rather not have!" Derpy looked sympathetic "I know what you mean, every time I get wet I feel the same" Applejack dropped her regulator, "You've got to do this Rarity, the map needs all of us." Pinkie echoed "C'mon, this is fun! I love breathing underwater!!" Quickly replacing their masks and regulators Rarity's dive buddies stood by as a flustered Rarity tried to let some tears go unnoticed down her already-wet cheeks. "it's just...just getting this thing to breathe right, I'm sure I'll be alright..."
"You've got your buddies by your side, they wouldn't let you come to harm," Derpy spoke as she waved Applejack and Pinkie Pie closer to Rarity, one on each side. "Okay, mask down.... regulator in your mouth..." Rarity placed the mask over her eyes and nose then nervously replaced the regulator in her teeth and breathed through the hissing valves. AJ and Pinkie took Rarity's forelegs in theirs, holding her steady in the shoulder-deep pool; Derpy pushed her mouthpiece in place and gave a "down" signal and lowered herself under the surface. Rarity gave a little squeal as she felt her partners lowering themselves along with her under the surface, her mane awash she breathed excitedly through the regulator; bubbles rumbling alongside her muzzle she tried to lurch upward but was held by both buddies. Rarity stopped bucking, chuffed a breath in near-panic then reflexively took a deep breath and felt faint... and wasn't drowning! "Breathe, breathe," she kept telling her body, and it was obeying. Rarity's heart loosened in her chest, slowing to near-normal as she breathed out a long stream of bubbles, then breathed in again. Muffled cheers from her partners were joined by her own bubbly giggling, she was finally becoming accustomed to this strange new way of breathing!
Once Rarity had calmed Derpy pointed to her, as AJ and Pinkie let her legs free and sat next to their partner, still breathing steadily through their scuba gear. Derpy took her reg out, held it away from herself while letting a small stream of bubbles escape her lungs. She replaced it and blew the water out of it then resumed her regular breathing. Rarity likewise removed her reg, blew some bubbles to keep her airway open, replaced it then huffed the water out to breathe the cool dry air from her air tank. Pinkie watched excitedly, this next step was the last before Rarity could move on in the dive class, "flooding and clearing". Applejack stood by ready to assist her if she panicked again.
Derpy lifted her mask off her face, a cloud of bubbles rushing to the surface. The mask went back on, then Derpy held it on her face as she exhaled from her nose, the air exchanging with water inside her mask. In half a breath it was clear, she could then see Rarity clearly and pointed, inferring "Rarity's turn."
"No magic" was the rule laid at the beginning of class by instructor Derpy. Rarity slowly brought her hooves to her mask, clamping down on the edges, taking a breath. She then closed her eyes and lifted the seal off her face and felt the water flood her mask, over her nose and eyes! It was still a shock but not as bad as the last few attempts, she just had to remember to breathe through her mouth to keep the water out of her nose. Slowly she opened her eyes to a blurry but recognizable Derpy sitting in front of her watching as she reapplied her mask. Pulling the straps back into place she put a hoof on the mask's front rim then blew into it with her nose. The bubbles began ticking her muzzle as they floated up, displacing the water out from under the skirt of her mask. "Keep calm, breathe..." Rarity had already run out of air and had to refrain from inhaling through her nose as she took another breath through her regulator. Still holding the mask firm she breathed out again this time clearing the water out with breath to spare. An elated Pinkie gurgled next to her, along with a firm shoulder-bump from AJ. Rarity smiled around the mouthpiece and nodded, "flood and clear" checked off.
Derpy clapped her hooves in joy, then waved the girls to the deeper end of the pool. Wings lazily flapping herself backwards she kept watch over her 3 tardy students, then turned to join the others in the deep. Forming a circle on the bottom all were happy to see Rarity had gotten over the first steps. Their lessons, and mission could now continue.
The six students and Derpy spent the better part of an hour doing simple but necessary skills. There were going to be more lessons before Derpy could release her students to the waters of Equestria but today's was over. Ditching their gear, washing off and stowing properly done the usual drying-towel-play began along with more questions for their teacher. Mostly technical questions but a few personal, one of which rather shockingly brought everyone to silence.
"I wasn't always cock-eyed, Rainbow..."