A/N: This was inevitable, when Nautilus's new skin was revealed. We both knew this would happen~

Wanted to make this a bit longer, but turns out trying to lengthen out a scene with a creature that lacks arms, language, and is underwater is quite tricky.

That aside, do enjoy~

Instincts

Summer was steadily nearing its end, in the Eagle Union.

Perhaps because of that a group of Destroyers and Submarines teamed up, formed a petition and got some time off from their usual duties. Their vacation plans whisked them away to Hawaii for a 'temporary deployment' and the Destroyers all headed out for some free-diving; three hulls carrying all the girls, Submarines included.

Nautilus found herself sitting on the back of Allen M. Sumner's hull, kicking her legs quietly as she waited to reach their destination. Already the busy islands of Hawaii were becoming somewhat distant – far from out of sight, but they were easily a mile or two out by now, probably a fair few more. This far away they were unlikely to encounter any human divers and would have free reign to explore the coral reefs in the area, especially one that Archerfish had located the last time she visited Hawaii.

The chatter on the boat was full of life, and even from her spot on the back of the hull she could hear the various ongoing conversations, some blurring into others and words getting jumbled up. Some spoke of diving, others of what they'd do when they got back to base, and others of coming back to Hawaii for some souvenirs.

She was excluded from them mostly out of choice. She preferred being back here, where it was quietest.

That was until Allen M. Sumner's voice came over the intercom. ''Alrighty! We're almost there everyone, so prepare to hop off~!''

A clamour came from the cluster of Destroyers and Submarines further on the boat, and with a quiet sigh Nautilus stood, prepared for the chaos – the back of the boat was the best place to hop off, after all. Idly she adjusted her new swimsuit, the bright yellow bikini a bit too eye-catching for her tastes, but admittedly she liked the colour a lot. Archerfish, who had helped pick it out for her, had agreed – and it was a damn sight better than the skimpy micro-bikini Albacore plucked out for her. How the blonde could swim about practically naked she never understood.

Chasing away such thoughts Nautilus shifted over towards the very edge of the boat, over where the depth charges were normally racked – though given the company being kept, Allen had the foresight to not bring any with her, mercifully. As the other girls all gathered nearby, still chattering on, Nautilus spared a glance at the various swimsuits present. From the dark blue bikini Allen wore to the frilly one Hobby had on her; there was a wide range of styles that all suited each girl well.

Mindful not to stare Nautilus waited until a couple of ships climbed over the railing and hopped off before doing the same, her heels touching the edge of Allen's hull – and then with a hop, she leapt off. Her heels hit the water a second later and she plunged down under the ocean's surface but she felt no fear, opening her eyes easily and gazing around at the deep blue waters, some shoals of fish swimming by and the occasional solitary sea creatures moving about in the distance.

Bubbles foamed up as others plunged down and Nautilus mindfully swam underneath Allen's hull so nobody accidentally dropped on top of her. The seabed was shallow here; a natural shelf rife with coral and rocks, forming a virtual maze below the sea's surface. Some ships were already going down to explore, the Submarines taking the lead given they were more familiar with diving than most of the Destroyers present.

Nautilus, for her part, decided to go off on her own – quietly swimming off to an isolated part of the coral and exploring. She found some crabs that snapped at her when she got too close but she didn't mind; just keeping her distance and watching as they side-walked away and down into holes in the rock, only to pop up at other places. Fish swam by her but didn't really react to her, not when she was so still, enabling her to feel the water rush against her skin as they just-barely swam over her back.

It was then that she heard a distant chipper-like sound, a familiar one at that. A dolphin's call.

Nary a second later she spotted a pod of them nearing their small flotilla. They swam up with surprising speed, some slowing near her before going up to the ship, whilst others went over to the others. Nautilus could only watch with fascination as they swam about, how natural their movements were and, soon, how they interacted with the fleet – squeaking and clicking as they swam around them, earning fear from some and cooing from others, Albacore taking the chance to pet one.

When the dolphin didn't react negatively the others decided to do the same, and before Nautilus knew it they were all petting or playing with the dolphins. The dolphins for their part seemed to enjoy the attention – some of the pod swimming off to do their own thing but others sticking around, playing with the others Ship-Girls.

One such dolphin came over to Nautilus herself, whining and clicking as it swam around her.

''H-Hey...'' Nautilus breathed out, bubbles escaping her mouth as she spoke. ''Easy...''

As if sensing her nervousness the dolphin floated up to her and bumped her stomach with its head, and tentatively she petted it. The creature made another whistle-like sound and didn't react badly, assuring Nautilus and prompting her to pet the animal more, a confidence fuelled when it swam around her and made several more happy-sounding whistles.

Thus it was a surprise when, out of the blue, the dolphin darted in and nipped at her bikini top – and Nautilus squeaked as, with one quick tug, it removed it. Reflexively she covered her small chest but the dolphin had already begun to swim away with her top, forcing Nautilus to uncover her small boobs as she swam after the animal, her whimpered 'hey!' going unheeded by the creature.

Eventually the dolphin slowed down, but when she swam up to it to grab her top it suddenly dived under her, getting behind her. She spun but then it went behind her again, toying with her – earning a whine of frustration from Nautilus as she tried to catch the playful animal. In the back of her mind she knew it probably didn't mean it maliciously, but having her boobs out – even if only her friends were around – was still an embarrassing thing, and she'd much rather have her top back in its rightful place.

''Come on, give it back...!'' Nautilus whined, trying another grab.

To her surprise, the dolphin let go of her top. Only to then push its face up against her demure breasts and nuzzle them, bringing a bright blush to Nautilus's face; the Submarine left paralysed with indecision as the dolphin rubbed its snout against her tits. She wasn't very big but the sensation, the pressure, send a shiver up her spine she wasn't entirely against. Especially when its tongue suddenly lashed out of its mouth, licking her right nipple.

Nautilus gasped, bubbles spewing from her mouth and foaming up to the surface, but the dolphin was unfazed and licked her nipple again. The rough texture of its tongue made her quiver and she wasn't sure whether to push the animal away or just let it continue – and in the end, she let it do the latter, overcome with embarrassment yet unable to deny it felt shamefully good.

So enraptured with the sensation was she that she didn't notice the creature shift down – and Nautilus flinched as it tugged on her loose bikini bottoms, pulling them off too.

''H-Hey- AH~!''

The water quelled the noise of Nautilus's cry, but her alarm was strong all the same as the dolphin pushed its head between her slim thighs, licking her pussy. The sensation sent a jolt up her loins and made her feel all sorts of ways she was pretty sure she wasn't supposed to feel with an animal, and in her distracted state she lost sight of where the two halves of her bikini went; fluttering down out of sight somewhere in the coral.

Left completely nude in front of a wild animal Nautilus wasn't sure what to do; embarrassment inclining her to cover herself but the pleasure that stimulated her nerves holding her back. Then by chance her eyes flickered down and she noticed the long pink cock protruding from the dolphin's lower half, the sight causing her heart to skip a beat. Not a moment later the dolphin swam closer to her, clicking as it rubbed its dick along her pussy and up her groin, its humping motions pushing her back but just prompting the creature to insistently hump her belly more.

''N-No, we can't...'' Nautilus feebly protested, covering her pussy with her left hand and pushing it back with her right.

But the dolphin was insistent; whistling in a tone that sounded almost sad as it pushed at her clasping palm, trying to expose her opening once more. She parted her fingers as she tried to adjust her hand but the dolphin quickly licked at her exposed slit, sending a jolt through Nautilus, the brief burst of warmth so enticing she her will to resist wavered almost immediately. She'd only ever used her fingers to pleasure herself before – what would it be like to have something bigger inside?

'But... it's an animal... and what if the others find me doing this...?' Nautilus was wrought with indecision.

The dolphin though pushed at her hand again, and this time she let it do so. Slowly swaying her legs she kept herself floating as the animal pushed itself against her, its long cock rubbing up her belly and making her whimper, feeling it thrust against her and try to get inside. It kept missing, unable to find her opening, so with some hesitation she reached down and spread herself open with two digits, awkwardly trying to guide it in without actively touching its cock.

'Come on, please... p-pleas-!'

Its tip grazed her opening – and Nautilus gasped out bubbles as the creature penetrated her. It claimed her first time in a single quick thrust but the pain wasn't nearly as intense as she expected, just a slight twist of pain that was overshadowed greatly by the foreign intrusion thrusting into her – the dolphin clicking and whistling joyously as it pushed itself up into her, its animal dick reaching her deepest parts with ease.

'O-Oh god... it's reaching so deep...' Nautilus thought to herself, writhing as her womanhood was filled.

She held onto the dolphin as it did all the moving, thrusting itself up into her and taking her along for the ride. The fact they were just floating in open water made it all the stranger, as she struggled to keep herself floating while the dolphin's body pushed and shoved itself against her, her legs seizing up as unfamiliar pleasure raced through her veins.

It was rutting into her like the animal it was; not stopping to check if she liked or didn't, whether she wanted to change positions or anything – it cared not about that. Instead the dolphin simply kept thrusting, kept burying its long cock into her formerly-virgin pussy and making Nautilus cry out, the sound lost to the water as her feeble resistance began to wither away into pure submission.

And with it came pleasure. The way its length jammed into her so roughly, so animalistically, left Nautilus holding onto the dolphin for dear life – any discomfort replaced by tingling warmth in her loins, far more intense than her own fingers could ever bring. She tried to wrap her legs around the animal but found it hard, her muscles quaking as she was railed raw. She couldn't even pretend that the dolphin was raping her, as the animal was known to do – she was into it, if shamefully so.

The creature's length jammed into her, twitching against her clenching walls – when suddenly the dolphin squeaked, and gushes of liquid warmth shot inside of Nautilus.

''Myn~!'' The Submarine whined through pursed lips, shuddering as the animal came inside of her, its seed spurting within her sensitive pussy.

A shudder convulsed through her lithe frame as the creature ceased cumming, leaving her so achingly edged but not quite there yet. She was about to try and swim off of it then – when a moan escaped her as the dolphin seemed to get a second wind, thrusting itself up into her and stuffing her sensitive pussy with its cock. Edged as she was every slight thrust set her nerves alight, pleasure aching through her loins and making her weak in the knees.

It was a surprise then when a second dolphin swam up behind her, revealing itself only because of the noise of its motion – and Nautilus squeaked as it pushed against her ass. It humped her in much the same way as the other dolphin had, its long cock gliding between her ass cheeks until it found her asshole-

''Ah~!''

-and then, perhaps inevitably, penetrated her asshole. The sensation of being deflowered was one thing, but having a cock in her ass was an entirely different sensation, her nerves alight with novel sensations as the dolphin bucked its body and eagerly drove itself into her rear. Incidentally this left Nautilus trapped between the two dolphins, moaning senselessly as her pussy and ass were used by the wild animals, their long cocks plunging up into her tight holes.

She didn't even try to resist – it felt too good. Having their inhuman cocks scrape at her insides, feeling the tip of one prod at her cervix, having their large bodies push and pin her between them – it was all so new, so fantastical, that she was just going along for the ride at this point. Her ass stung slightly from the harsh impacts against it and her groin ached a little but outside of that she felt nothing but pure pleasure, her skin tingling with warmth despite the mild water around her, overwhelmed by the foreign pleasure invading her lithe body.

'What would the others think? Would they join in? Are they doing this right now in a big, dolphin orgy...?' Nautilus thought to herself, lips pursed to preserve air – but every time one of the dolphin's cocks rubbed her sweet spot they parted in a moan. Small mercies Submarines like her didn't need to go up for air nearly as often as a human would.

If anything that just made the dolphins use her holes more roughly, as if confident she could handle it. Their dicks jammed up into her and Nautilus cried out, bubbles spewing from her open mouth as she felt her loins be utterly stuffed – hard, fast thuds against her deepest parts making her see stars, her petals parting for the creature's plunging cock. Her asshole clenched around the intruding dick there too but the dolphin just clicked its joy, the tightness no doubt encouraging it further.

The friction, too, pushed Nautilus towards her own end too – her previously-denied orgasm coming back to bite her. The fiery need in her loins grew exponentially and she struggled to think of anything but the pounding cocks in her holes, her insides tingling and tensing, her breath bundling in her throat-

-and then she came, wailing as she did so. The sudden tightness that clenched around their dicks pushed the dolphins to their own limits and she felt their hot seed pour into her holes once more, filling her pussy and asshole with spurts of animal seed. She jerked and spasmed like she was shocked, her insides forcibly filled with dolphin semen and leaving her mind utterly white, never having felt as good as she did then and there.

Eventually though she came down from cloud nine, shuddering, when the dolphins pulled out.

''Ah...'' Quivering at their absence Nautilus looked between the two, blushing as they both nuzzled her breasts in particular.

Then with naught but a delighted chirp the two dolphins swam off, presumably to go join their pod once more.

Leaving Nautilus naked and alone.

'...um... where did my swimsuit end up...?'

When she returned nobody noticed anything amiss, mercifully.

The dolphin's act known only to her.

[END]