Download, View, and Print Maps with the MrSID Viewer.
To download and view maps offline you need a special viewer. Maps are stored in MrSID format. The MRSID Viewer is a freeware tool. This library provides access to the MrSID viewer developed by LizardTech.
LizardTech dropped the link for that stand-alone viewer download from their website some years ago, and now they only offer a browser plug-in that only allows viewing of MRSID images, and command-line utilities that convert the entire MRSID file into what could be an enormous TIFF image file.