WordNet sense 1 (the limit of capability):

grasp, range, reach

WordNet sense 2 (an area in which something acts or operates or has power or control:):

orbit, scope, ambit

WordNet sense 3 (travel around, either by plane or ship):

circumnavigate

WordNet sense 4 (get the meaning of something):

apprehend, comprehend, dig, savvy, grok, get the picture