GPS is the main tool you will have to use to navigate yourself and the locations. You will see purple exclamation marks, which are the locations of the GPS Locators with the people who died with them. You can change the marker icon by changing it through the GPS Locator you take from there. The cave markers are the typical enterable caves that either has equipment, weapons, materials, and supplies to take from. The green blinking markers are the bunkers that either you will need a shovel or a keycard to access. You can find 3D Printers in them but not in all of them.