You'll find missing optical disk locations around Brookhollow Park in Grounded 2; they'll be marked on your map almost right away. Since you're told where to look, you'd think they'd be easy to find, but they're missing for a reason.
In fact, the map markers can be somewhat misleading, as grabbing the missing optical disks generally involves delving into some pretty scary caves, only accessible far from the marker. So make sure you've geared up a bit before you track them down.
