This chapter analyses the International Maritime Organization (IMO) as a case study for global experimentalist governance in ocean acidification. Shipping significantly contributes to OA through CO2, NOx, and SOx emissions, along with scrubber discharge that releases acidic water directly into the oceans. The IMO regulates shipping but scarcely acknowledges OA, instead promoting scrubbers despite their harmful effects. The chapter assesses the IMO’s climate change response against experimentalist governance elements: (1) A shared problem exists – stakeholders agree climate change needs addressing; (2) Open-ended goals are present – the Revised GHG Strategy sets framework objectives like ‘reducing emissions as soon as possible’ with specific metrics; (3) Delegation occurs through National Action Plans (NAPs), where member states experiment with solutions; (4) Feedback and peer review are limited – only 9 of 175 countries submitted NAPs, with minimal systematic comparison or best practice identification; (5) Goal adjustment is possible through strategy reviews. A key limitation is that weak peer review and feedback mechanisms undermine recursive learning essential to experimentalist governance. While some experimentalist features exist, the IMO’s response only partially resembles this governance model, suggesting limited potential for addressing OA directly through experimentalist approaches.