Yangtze

The Yangtze is a Chinese nuclear missile submarine lodged in the shallow waters off the coast of the Commonwealth, near by The Shamrock Taphouse.

When investigated the submarine contains six launch tubes with one nuclear bomb still loaded (that the player can loot the [Warhead] from during [Quest]). Talking with [Captain] confirms that, on the day the nukes fell Yangtze had launched its payload as per orders, so its possible that the mushroom cloud seen at the start of the game was directly caused by the submarine.

Appearances
The Yangtze only appears in Fallout 4.