A modder has discovered a secret Fallout 4 weapon that appears to be intended for underwater use.
Modder xxdeathknight72xx discovered the Harpoon gun while rooting through Fallout 4's assets. It's bubbling animation indicates that it may have been intended for an underwater mission, potentially either one that was scrapped from the final product or one planned for an upcoming DLC. The harpoon gun replaces the Railway Gun in a player's inventory, and since it doesn't officially exist, a player will have to use console commands in order to pick up ammo for it.
Information on how to get the gun is available here.
Prior to this, players discovered a hidden treasure room that includes every single item in the game. The first beta patch for Fallout 4 is available now on PC, to be followed by a full release on all platforms.