It is helpful to cache basemaps inside of Site Scan Field before heading on site. Internet may be spotty, the tablet may not be LTE enabled, or you just understand the value of preparation.
The images below should provide a clearer idea of how this works. The basemaps that are served in Site Scan are tiled to enable rapid zooming and manipulation. Each zoom level is thus a different set of files to download.
Notice that I have not recently planned a mission outside of North America, so those tiles are not visible without an internet connection.
Likewise, the border between zoom levels I pulled is clearly visible. If I had wanted to capture the tiles from the Area of interest at this zoom level, I would have navigated to the area while connected to the internet.
Despite being disconnected, with the maps cached I can plan my mission at the highest zoom level.