Altis, Arma 3’s main island, is huge. With a ground surface area of 270 km2, and vast water and underwater locations, its total area clocks-in at almost 1000 km2 of highly detailed environments capable of supporting land, air & sea combat.
It’s so large that most people have trouble understanding such scale in a video game. The surface area value is not really descriptive, and even comparing it to our previous maps (e.g., 1.5x larger than Chernarus) really explains nothing if you never played our games before.
But you probably played other games. Who doesn’t know about the mountains of Skyrim, or the prairies of Red Dead Redemption? So I did a little investigation and prepared some images, one comparing all Bohemia Interactive terrains, and the other pitting Altis against the terrains featured in other famous games. While the former is using exact sizes based on our internal data, the dimensions in the latter are approximated based on what I was able to find in the respective games and on the internet.
I hope it will help you to understand the scale of worlds not only in Arma 3, but in other games as well.