As is the case with any big release, chances are that people will get the game before official release, and this is no different with The Legend of Zelda: Breath of the Wild (it was recently pirated on Wii U, for example). The latest leak includes the entire map of the game.
Yes, a user on GameFAQs leaked the map, saying: "A complete high-resolution map has been created from the game files. There are no borders, markings or annotations of any kind. Maybe anyone of you wants this so they can decide which direction they want to go first, or what specific map features to check out first?"
If you want everything totally fresh, we suggest you don't follow the link, but if you want some insight into the locations in the game, by all means go ahead. Are leaks like this useful, or frustrating?