contour lines

You ca download contour lines from here:
https://garmin.opentopomap.org/#download

Thank you for the reply.

-Using your method that worked for my 810 as well, is it possible to have multiple maps (countries) at the same time? 

How do I rename the multiple map files in order to be recognized by the device?

-It seems like the newer devices have this option of displaying the contour lines, see the advanced menu here:

Edge 1040 Owners Manual - Map Appearance Settings (garmin.com)

My question is if this option requires downloading the the topomaps you mentioned in worder to work anyway.

You can rename the files. The Garmin devices don't care about the names. The different files need to have a different internal ID number if the they used for routing. Since the contour line maps don't have routing information, the ID in the file shouldn't matter (I suppose it's possible it shouldn't be an ID that a routable map is using).

You should be able to use multiple contour overlay maps at a time.

The newer maps included with the Edges have contour lines and the newer Edges have an option to display them or not (sort of the same way that the display of other map elements might be able to be turned on or off).

That is, the units that have the option to display contour lines don't need any other maps.

The way the method Medomish  mentioned works is a bit different. It uses an "overlay" map that is displayed on top of another map.

Thank you for your informative reply. 

I am pleasantly surprised that the newer Edges have the contour line built into them, but I was not able to determine that for the Explore 2, only for the 1040 as mentioned in my second post. 

It would be much appreciated if if anyone would confirm this.