The Yangtze-31 (Chinese: 扬子-三十一;), is a Chinese nuclear-powered ballistic missile submarine commanded by Zao. When first discovered by the Sole Survivor in 2287, it is lodged in the shallow waters off the coast of the Commonwealth south of Boston Airport and northeast of the Four Leaf fishpacking plant. The submarine is not marked on the map until the Sole Survivor swims out to it. Upon discovery, the quest Here There Be Monsters will automatically be started if it hasn't been received already from Donny Kowalski near the Shamrock Taphouse.