The Invincible-class submarines, formally classified as the Type 218SG submarines, are conventionally-powered diesel-electric attack submarines built for the Republic of Singapore Navy (RSN) by German-based naval conglomerate ThyssenKrupp Marine Systems (TKMS). Tailored to the operational requirements of the RSN, the model is derivative of the export-oriented Type 214 submarine, with specific design characteristics drawn from Type 212 submarines. They feature several additional capabilities, including a substantial level of automation, a significant payload capacity, enhanced underwater endurance and superlative ergonomics.