Marina's swim continued, as the light of the surface above grew dimmer and dimmer. Soon, she was in total darkness, and yet, the amulet glew brighter and brighter the deeper she went. It was compelling her to keep going.
Her tail grew longer, more muscle mass bulked up in it, accentuating her slender waist even more. A pair of triangular fins pushed out of her hips, affording her better directional control as she powered through the water towards some unseen goal. It was at the bottom of the sea, it felt, in the deepest depths of the ocean. Marina could feel it pressing in around her, and soon enough, she had to stop.
The pressure was too much, this was the limit that she could dive down to. It was pitch black, save for the glow of the medallion. Marina turned over onto her back, curling her body to better examine it. She had been swimming for so long that she hardly noticed the changes. It was hard for her to turn her head down, as if her neck muscles had merged with her jaw muscles. But, with her increased range of vision, that was no matter.
Her belly had turned white, she looked like an orca almost. And while her skin looked like it was still made of neoprene, she knew it wasn't. No, it wasn't synthetic anymore. It was a part of her, like the medallion, and the sea.
She couldn't say anything about it, either. Her vocal chords were gone now. Marina gulped down a breath of water. More than that, the curve of her bust was reduced a lot, yet, she knew she still had them. An experimental press of a fin told her that area was still sensitive, but, not nearly as sensitive as before.
Looking to her pectoral fins, they were no even less dexterous than before. She couldn't curl them, and while they were the same length, they sprouted right from her body, as opposed to looking like they were on her forearms.
Then, one last change made her spasm, hot pleasure surging through her form. With that pleasure came arousal, emanating from her intimate area, as a long slit opened between her hips. A pair of small fins formed on either side. Marina gasped in a breath of water, and would have moaned if she still could, as her cloaca finished forming. Her mouth gaped open in the throes of an orgasm.
She was shocked out of it when cold water surged the opening, and found it was more than easy to close it. With that last change, Marina felt… almost complete… She could feel fin, this one pushing out of her back, long and triangular. A dorsal fin. Then, something… felt. She turned her head in its direction. Marina felt something… moving… in the water. She could sense it.
Along her face, neck, and shoulders, which had slimmed down greatly, she felt it, the movement. Something instinctual gripped her. Hunger. Her face had narrowed to a point, eyes pushed further apart to give her an even greater field of view.
The thing that was moving, it was prey.
Marina darted towards it with newfound power, not realizing that she had grown to one and a half times the size of a great white shark. However, as she swam towards that prey, and realized her teeth were so sharp, her senses so tuned, her swimming so powerful, she realized that she was a predator of the depths. A hunter of fish. It was exhilarating.
She swam off at top speed towards this prey, not a thought in her mind about the life she was leaving behind on the shores she had come from. As she hunted, she realized that she finally… felt… complete.