Ocean chemistry has been almost exclusively based upon retrieving samples from the ocean for laboratory or shipboard analysis, or deploying sensors to recover natural signals. The ability to execute complex experiments in the deep ocean akin to the manipulations carried out in laboratories has largely been absent. In this paper, we review the progress made in manipulating and sensing complex gases, liquids, and solids in real time in the deep sea to advance understanding of natural processes. These experiments were made possible by access to the remarkable capabilities of Monterey Bay Aquarium Research Institute’s (MBARI’s) remotely operated vehicle and the skills of the operational teams. Here, we report on advances made in methane hydrate research and deep-ocean Raman spectroscopy, and on proposals for fossil fuel CO₂ sequestration and on controlled ocean acidification studies. The skills necessary to advance this work have been made possible only by the joint efforts of engineers and scientists as envisaged by MBARI’s founder. We note with some concern that in reporting progress here there were few antecedents to draw upon, so that the citations listed have a distinctly unbalanced look. Nonetheless, the impacts of the institute’s work have been far-reaching.

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