Russian submarine Losharik

Project 210, Project 10831 or AS-31, nicknamed Losharik, is a Russian deep-diving nuclear powered submarine. On 1 July 2019, a fire broke out on the vessel while it was taking underwater measurements of the sea floor in Russian territorial waters. АС stands for Атомная Станция (Atomnaya Stantsiya), from the Russian naval term атомная глубоководная станция, 'nuclear deepwater station'. The submarine is also known as AS-12, but this number is assigned to another vessel.