To browse Canadian topo maps online you can use This site
To download the topo sheets as 300dpi zipped TIFF file: Use the interactive map on this site to locate the map sheet you want, and then type the sheet number into the boxes below to download a digital scan of the topo map sheet.
You can then crop these sheet to your area of interest, print and take out into the bush
250K Square:
(eg. 82N)
50K Square:
(eg. 8)
USA Topo Maps
Topographic maps of the USA can be downloaded from the USGS website in PDF format