As mineral prices continue to rise and high-quality terrestrial supplies dwindle, hardrock mining will soon spread to the one place on this planet it currently does not occur: underwater. The United States has regulations permitting the issuance of offshore mineral leases, but these regulations rest on questionable authority from 1953 and are already obsolete even though they have never been used. The United States will need to adopt new legislation before it can effectively access and develop this final mining frontier. The history of American mineral law is littered with mistakes and scandals. But in this particular context, that tortuous past can have a silver lining if used as a precautionary tale: Learning from the mistakes of onshore mining law, onshore oil law, and offshore oil law, the United States has an opportunity to proactively reform underwater mineral law to responsibly usher in the future of hardrock mining. In light of this opportunity, this Comment examines three case studies from U.S. mineral law to extract lessons and suggests how such lessons could inform lawmakers in drafting a sensible offshore mining law.