Marina's hair was made of living seaweed, and it was dying because she had no place to plant it. The green fronds hung heavy down her back, dry at the tips, curling like they wanted soil. She had one dream. She wanted a stretch of seafloor to call her own, where her hair could take root and bloom into a tide-flower no one had ever grown. But every patch of coast she found belonged to someone else. Today she drifted over golden sand with nothing but her own two hands and a fading crown of weeds. The fronds shed as she swam. One strand broke loose and sank. Marina caught it, pressed it back against her scalp, but it would not hold. Without roots, her hair had weeks left. Maybe less. A hum reached her through the water. She turned. A bright yellow submarine rested on the sand, its round hull streaked with rust, portholes dark. Beside it stood a diver in an old copper helmet and heavy suit, moving slow and careful. He was tending something. A cluster of algae, planted in a neat row, swaying like ribbons. Marina swam closer. The diver looked up through his helmet's glass. He did not speak. He gestured at the algae, then at her hair, then held up one gloved hand: wait. He pointed past the submarine. Marina followed his arm and saw it. A worn iron key, half-buried, wrapped in shells and thin green weeds. The weeds around it grew thick and bright. Whatever soil held that key, it fed sea plants better than any patch she had seen. She reached for it. The diver caught her wrist and pointed the other way. A fish-shaped sign stood crooked in the sand. Bold letters warned of a fish hook. Marina saw the barbed line then, strung low across the key, waiting to snag anything that grabbed for it. She pulled back. The diver nodded. Then he did something she did not expect. He knelt, dug his gloved fingers under the hook line, and lifted it clear. He held it up for her to see, then set it aside in the sand. Marina dug the key free. Beneath it the seafloor was dark and rich, threaded with the same bright weeds. She pressed her hands into it. Soft. Alive. This ground could hold roots. She looked at the diver. He tapped his chest, then swept his arm across the whole stretch of sand around the submarine. A gift. Or a trade she did not yet understand. Marina lowered her head to the soil and let her hair spread across it. The fronds gripped. For the first time, her seaweed took hold. She felt it pull, drink, settle. She had her coast at last. But the key still lay in her hand, and the diver was already watching it, waiting to see what she would open.