The db-wide Activity Log can be exported using the Bulk Extract (preferred) or Bulk Export API. You'll need to be/have a developer for this task.
When done, you'll have a -- potentially gigantic, depending on time range and data volume -- set of files.
Obviously, knowing which activity types you'll be crunching ahead of time will reduce the file size/time to complete accordingly.
Thanks for the response Sanford,
I didn't think about the Bulk Extract, thanks for the heads up. Also, you're correct, I should spend trying to identify what exact activity i'm looking for before getting our developer to perform any large extraction. Thanks again