Scientists are exploring the ocean as a potential source of critical minerals needed for batteries, electronics, vehicles, and clean-energy technologies. Pacific Northwest National Laboratory researchers estimate that just 0.1% of Earths seawater contains enough magnesium and lithium to meet humanitys needs for 50,000 years or more, if fully extracted. Yet extremely low concentrations make recovery expensive and energy intensive. Researchers are testing approaches involving magnesium hydroxide, desalination brine, specialized membranes, and mineral-accumulating seaweed.