USV Maxlimer is a semi-autonomous, remotely controlled unmanned surface vehicle (USV) owned and operated by the British company SEA-KIT International. She was the winning entry in the Shell Ocean Discovery X Prize competition, and subsequently has been used as a proof-of-concept vessel for uncrewed, over-the-horizon offshore operations. History Maxlimer was constructed in Maldon, Essex, for the GEBCO-NF Alumni Team, an international group that competed in the Ocean Discovery X Prize. During the competition, which took place in late 2018, Maxlimer deployed a HUGIN autonomous underwater vehicle to map of seafloor in the Mediterranean Sea off the Greek city of Kalamata in 24 hours, an accomplishment that made GEBCO-NF the winning team. In May 2019, Maxlimer made a demonstration crossing of the North Sea between West Mersea, England and Ostend, Belgium. On the outbound trip to Belgium, she carried a cargo of of oysters, and on the return a case of beer. Though largely ceremonial, as the voyages were for the purposes of demonstration, SEA-KIT states it was the first commercial autonomous crossing of the North Sea. In July, the USV Maxlimer again deployed and recovered a HUGIN Unmanned Underwater Vehicle (UUV) several times in commercial service for Equinor to inspect offshore underwater pipelines in the North Sea - the first time that inspection equipment had been remotely controlled past line of sight. SEA-KIT intended to send Maxlimer on a transatlantic crossing in early 2020 as part of a project co-funded by the UK Space Agency through the European Space Agency’s Business Application programme. This would have been the first ever unmanned crossing of the Atlantic, but as a result of restrictions imposed during the COVID-19 pandemic, the voyage had to be cancelled. Instead, in July 2020, Maxlimer sailed from Plymouth on a 22-day mission to map about of previously uncharted seafloor southwest of England on Europe's continental margin. The project aimed to demonstrate the capabilities of current technologies to survey unexplored or to-date inadequately surveyed ocean frontiers and served to prove the capabilities of SEA-KIT's USV design, namely long endurance, over-the-horizon capability and ocean-going ability. With its project partners, SEA-KIT demonstrated the ability to conduct remote survey operations with safe control of the USV via satellite communications from anywhere in the world. The Atlantic mission was covered by BBC News. Design The SEA-KIT X-class USV, of which Maxlimer was the first, is a remotely controlled, configurable mother-ship platform that can