On land, the concept of rewilding has been gaining traction for decades. There is a growing understanding that putting nature in charge, allowing re-growth, restoration and resilience-building at the planet’s own pace, can bring untold benefits for humankind and may be one of the key tools at our disposal in fighting the climate crisis. In the ocean, while the conservation sector is well-versed in the terminology of marine protected areas there has been little discussion of marine rewilding. For the purposes of the day, Blue Marine defined rewilding the sea as any effort to improve the health of the ocean by actively restoring habitats and species, or by leaving it alone to recover. Blue Marine is dedicated to seeing the ocean restored to health. The frame of ‘rewilding’ in the marine realm is new, but offers real opportunity for fostering a new understanding of, and respect for, the role of the ocean itself in building complex, resilient ecosystems. Ecosystems that could be crucial engines for biodiversity on an increasingly nature-depleted planet, and that could create huge marine carbon sinks to buffer against the negative effects of climate change. Requiring a move beyond traditional target-setting and an acceptance that the outcomes of rewilding projects may prove surprising (including the possibility of more interconnected and more abundant benefits than anticipated) is a challenging new opportunity for ocean advocates to grasp. To explore how rewilding might apply to the marine realm, and take inspiration from existing case studies on land and at sea, Blue Marine convened an international, digital conference on June 24th 2020. The conference had three core ambitions: 1) To unite the marine restoration community ahead of the UN Decade on Ecosystem Restoration, 2) To overcome regulatory challenges that hamper current restoration efforts, 3) To introduce a new audience of maritime businesses, funders and politicians to the topic of marine rewilding. The digital delivery of the event allowed over 1,500 people to join the morning sessions, hear from expert speakers and share their views online (a recording of the day has attracted over 3,000 viewers). A smaller, focused gathering in the afternoon included break-out rooms to identify key takeaway messages against headline themes.