When viewing a PDF document in Acrobat Reader, you will notice a band of icons immediately above the document you are viewing. The plus symbol will always be available, and depending on your Acrobat program you may also see a magnifying glass.

Simply click on the plus sign to increase the magnification of the whole map and then use your horizontal and vertical scroll bars to scroll to the area you want to view. Or choose an ideal magnification by selecting a percentage in the drop-down menu next to the plus sign.

Alternatively, you can magnify a specific spot on a PDF map by clicking on the magnifying glass icon, then moving down to the map, centering the magnifying glass on the spot, and clicking again. Continue clicking to zoom in more.