This startup wants to build a fusion reactor — on a boat

Maritime Fusion, led by CEO Justin Cohen, is pioneering the development of a fusion reactor designed to operate on a ship, aiming to leverage recent advances in fusion technology to bring clean, abundant power to maritime vessels. While fusion reactors have traditionally been developed on land, Cohen believes that placing a tokamak—a leading fusion reactor design—on a boat is feasible and potentially advantageous. Unlike nuclear fission reactors currently powering some submarines and aircraft carriers, fusion promises similar benefits without the risks of meltdowns, radiation, or proliferation. Maritime Fusion’s approach also targets a unique market niche: the high fuel costs at sea, where fusion could compete economically with expensive alternatives like ammonia and hydrogen, unlike on the terrestrial power grid where solar and wind dominate. The startup has raised $4.5 million in seed funding from investors including Trucks VC, Y Combinator, and angel investors, and is actively developing critical components such as high-temperature superconducting cables essential for the tokamak’s powerful magnets. Their first