Modern aquarium planner and veteran diver Jiang Yu accidentally time-travels to an ancient fishing village, becoming an 18-year-old youth burdened with fifty liang of debt, while his widowed sister-in-law and young niece are about to be used as collateral. Relying on his professional marine knowledge, he ventures into dangerous shoals to hunt moray eels to pay off his debts, improves fishing and preservation techniques, and achieves a dimensional-reduction breakthrough in the fishing market. Along the way, he resists plots from local ruffians, encirclements by wealthy merchants, and difficulties made by conservative forces. Seafood merchant's daughter Lin Zhixia shifts from contempt to appreciation, starting a business alongside him. Jiang Yu builds a massive seafood business empire, protects his family, wins love, and rewrites everyone's destiny by the sea.