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
USA Topo Maps
Topographic maps of the USA can be downloaded from the USGS website in PDF format