长江31号 (Yangtze-31)是赵船长指挥的中國弹道导弹核潜艇。2287年，老冰棍探索发现该艇時，它被困在波士顿机场以南、四叶鱼肉包装厂东北部的联邦沿海浅水区。The submarine is not marked on the map until the Sole Survivor swims out to her. 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.
Shortly after firing its strategic missiles, 长江号遇到了水雷瘫痪，好不容易才来到了岸边，此时潜艇不仅失去了动力，上面的船员们因为辐射也都慢慢变成了狂尸鬼，仅剩赵舰长一个人成了还有意识的尸鬼。
The Yangtze is a unique design for a ballistic missile submarine.三具倒三角倾斜布置的大直径螺旋桨在艇身中部，其中下方的螺旋桨在核反应堆控制室后。The sub's design is unique as所有设备都位于艇身前半，后半结构细长，方向舵带有小型螺旋桨。
The first room the Sole Survivor comes to when entering the submarine is the control room/bridge where Zao is located.
Down the stairs is the reactor control room with a radio room on the port side (left when facing forward). There are two doors on either side of this room that go to a small room with a cage wall and a large machine behind which is presumably the propeller drive shaft.
Behind the reactor room and under the bridge is a room with the machinery and instrument panels. On the port side of the room is Captain Zao's quarters and on the starboard side is the officers mess.
Forward of the reactor control room is the upper reactor level and contains the reactor access hatch and a stairway, on the port side, leading to the lower level. The lower level contains reactor machinery and two doorways, at the rear, leading to the engine room for the lowest of the large propellers.
Past the reactor room on the upper floor is a small room that contains two decontamination showers and a locked door with a stairway to the lower deck. There is also a science lab on the port side of the room.
Forward of that room (still on the upper level) is the sub's mess room, galley, and food storage (the room opposite the galley). Forward of the mess is the crew quarters, containing 80 beds (configured in 8 stacks of three and 14 stacks of four), the sub's lavatories and a laundry room (port side), as well as the ships med-bay/infirmary (starboard side).
At the front of the quarters are two doorways that lead into each other at the front of the sub, then lead into a room on the lower deck that contains machinery with a workshop on the starboard side and a storage room on the port side. The next room contains a doorway on the starboard side leading to the sub's armory, and a hallway at the end leading to the silo room.
The silo room contains the 6 missile silos with 3 along each side. Each silo has an access hatch that allows the crew to access the SLBM inside. All are closed except the one with the missile that failed to launch. The next room is a small room before the reactor room which contains a locked door to the upper level. Unlike the only other Chinese submarine the player character can personally encounter in the series, SSN-37-1A, the Yangtze is in fact a full-scale combat vessel with extensive crew amenities and visible missile and torpedo tubes. It is shaped very differently to any real-world submarine, unlike the SSN-37-1A, which bears a very conventional (albeit small) design.
- Submariner uniform and submariner hat - Worn by Captain Zao.
- 核融合核心 - 機組員起居區一個已經打開了的裝備櫃內。
- 核口可樂量子味 - 同上區，在一個握著核口可樂卡車的機組員骷髏旁。
- Chinese officer sword - Lying on a desk in the captain's quarters, a room underneath the bridge.
- 潛艇員帽子 - 大副身上，就在怪物出沒任務的標記點區域。
- 彈頭 - 同上。
- 隱形小子 - 在一個由專家難度終端機控制的儲藏區內
- Vault-Tec lunchbox - In the galley on the table in the southeast corner.
- 大副的密碼 - 大副身上。
- Hazmat suit - In the missile warhead room in an openable locker by the south door.
- 老趙的劍 - 只有在通過最難的魅力檢測後作為任務獎勵取得。
- Fusion core - Found in a box underwater near the generator on the lowest level when going down the steep stairs past a skeleton lying on a barrel.
- After using console command tmm 1 to reveal all locations on the map, Yangtze's location is not revealed.
- While Yangtze is a Chinese submarine and manned by a Chinese crew, her interior bears no Chinese characters (汉字) (Hanzi). Warning signs and terminals are also written in English. Furthermore, all other items present aboard seem to be of American origin (This is similar to the FMS Northern Star which is of Norwegian origin and also has the same problem, despite the fact that every person on board very clearly cannot speak English).
- In real life, the term Yangtze（扬子) is relatively unused in modern Chinese. Chinese people would likely use the much more popular term 'Changjiang'（长江）, while westerners use 'Yangtze'. 'Yangtze' would also have been spelled 'Yangzi' in modern pinyin, since 'Yangtze' is the romanized spelling.
- Oddly enough, there are various bottles of Nuka-Cola on the ship, including a bottle of Nuka-Cola Quantum. This is strange considering the hostilities between the USA and China, which would make it unlikely that the Chinese would drink Nuka-Cola. It is likely, however, that the American items were brought on board by raiders, which the Captain mentions have attacked since the bombs fell. This may also explain the presence of a Stealth Boy, an explicitly American invention based on reverse-engineered Chinese Hei Gui stealth armor.
- In the infirmary, a skeleton of an American serviceman can be seen on the bed with handcuffs and a bone cutter and surgical scalpel on a table next to his bunk. It can be assumed that he was possibly captured and brought on board when the sub arrived in Boston.
- It is difficult to get to the Yangtze while wearing power armor unless one uses the jetpack modification. To reach the submarine, one must swim without power armor from the shore or spawn at the fast travel point, which is on a nearby scrap barge. As it is impossible to swim in power armor, one must either sprint jump to get onto the Yangtze from the scrap barge that the fast travel marker spawns on or use the jetpack to reach the submarine.
- There are 4 torpedo tubes on the front of the submarine but there doesn't appear to be a torpedo room aboard the sub.
- The periscope/sensor mast of the Yangtze (confused for the eye of a monster by Donny Kowalski) is raised at times by Zao so he can observe what's happening near by.
- Settlers of the Commonwealth can be heard talking about a "ghoul whale" in the harbor. It's possible that they are referring to the Yangtze due to its shape being similar to that of the sperm whale.
- When visiting with Curie, she will note that humans are capable of wonderful things when they aren't trying to kill each other.
- It is very unclear on how Zao will be able to pilot the Yangtze out of the Commonwealth on his own.
- Items can be saved in the ship after the quest involving the ship is completed, meaning the ship can be used as a player base.
- The Yangtze can be destroyed during Here There Be Monsters when the Sole Survivor is tasked to replace the dampening coils and put a warhead in the reactor. However, the explosion will kill the Sole Survivor and Zao, even if the Sole Survivor manages to get out of the submarine before the explosion.
- When comparing the Yangtze's side profile to that of classical submarines, it misses a large section of the lower stern. The absence of this section significantly reduces its weight, adding to its speed. Combined with the angled hull in the front and the added propellers in the mid-section, the Yangtze would have had superior speed and maneuverability over classical tube-shaped submarines.
- Approximately thirty former crew members are encountered throughout the submarine. Some have died previously, leaving their skeletons strewn throughout the ship, and some have been transformed into feral ghouls.
- The doors inside the submarine are incorrectly called "bulkheads."
The Yangtze only appears in Fallout 4.
- Fallout 4 Vault Dweller's Survival Guide p. 507: "Easily mistaken for a strange aquatic monster, this Chinese nuclear submarine (Liao-Class Type 113) is hidden among the wrecks of other ships in the Boston Harbor. It is commanded by Captain Zao. Should you wish to access the terminal (Master) on the lower level, find the first mate’s password from the fellow lurking down in these parts."