[BarkMore]

The site http://caltopo.com/ is another good resource for maps. The site includes a number of maps including USGS, USFS and marine charts. There are several useful overlays for hikers including trails and fire history.

[tammer]

I'm a huge fan of a little app called Maplets.[1] Has saved me on a number of occasions, and highlights how limited the big name mapping tools really still are for all kinds of navigation information.

[1]: http://www.mobilemaplets.com/

[rasengan0]

Mee too, off to europe and maplets is my goto offline. https://www.openstreetmap.org/ and GPS on https://www.google.com/maps are supplements. What always surprises me is GPS working sans wifi and cellular

[toomuchtodo]

Thank you for mentioning this app. Purchased!

[rkcf]

I love caltopo. I use it for all of my backcountry adventures. It also has historical maps in its database which make for a good time finding ghost towns and possible ruins.

[mc32]

Fro topo I use these maps too http://www.arcgis.com/home/webmap/viewer.html?useExisting=1