So in preparation for my upcoming Hawaii trip, I stopped by the GGNRA book store and picked up my free Interagency Access Pass
All I had to do was show my doctor's note "This is to inform you that Ben has Type-1 Diabetes, a permanent condition that significantly limits and affects his daily life activities" and they handed me the pass. Took 3 minutes. The pass gives me and any passengers in my car free access to any national parks, discounts on camping and other things, and certain secret magical powers*
NOTE: Magical powers may vary and may be imagined.
Check out http://store.usgs.gov/pass/access.html for details. They also have a pass for the over 62 set, but I have a ways to go on that one.
For U.S. citizens or permanent residents with permanent disabilities.
May be obtained in person at a federal recreation site or through the mail using this application form. The cost of obtaining an Access Pass through the mail is ten dollars ($10) for processing the application (the Pass is free). Applicants must provide documentation of permanent disability and residency or citizenship.
May provide a 50 percent discount on some amenity fees charged for facilities and services such as camping, swimming, boat launching, and specialized interpretive services.
Generally does NOT cover or reduce special recreation permit fees or fees charged by concessioners.