Other than being able to get one million experience points in twenty minutes, there are plenty of other rumors that are coming out since the release of Fallout 4. The open world game is going to be updated and improved through downloadable content packs and in one of the upcoming, fans are suggesting that underwater play is next.
This could just be a rumor started by a hopeful fan and the lack of information regarding the game update has people questioning whether they can expect it in the next update. Either way, rumors are rumors and sometimes they come to light. Other times, they die when the studio decides to put an end to it.
Online forums have seen many different postings from fans of Fallout 4 and the digging around they have done within the game with hopes of finding some secret code that is going to be used at a later time within the game. One fan posted that he found a texture map for a squid and quickly questioned if it will be a new creature.