If you want more than one mapset loaded(streets, topos, lakes, ect.) you need to load them both at once. you do so by selecting the area you want of streets, then switch mapsets in mapsource and select the area you want of your other maps. now just upload to your GPS as usual.
The other catch is streets take priority over other mapsets, so you need to hide the streetmaps on your gps to see the other maps. It’s such a buried option that since your 60c only has 64mb of internal memory It may just be easier to load the different mapsets from the PC before you head out.
To show/hide mapsets on your gps, from the map screen press menu and select setup map. Highlight the mapsetup -information Icon(5th from left). You can show/hide individual map segments here, but if you press menu again with the i- icon highlighted you can show/hide entire mapsets.
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