The path can also be customized, in Preferences (F2)/Network/Cache
Something that took me years to notice (because this was different in IE): To
surf in the cache, one must explicitely tell this the browser: File/Work Offline!!
Unfortunately, if in offline mode some page isn't cached, KM won't tell this, it only reports something general like "page not found", making it look like the server were down, if one has forgotten to switch back to online mode... Firefox reports this ;-P