I was very surprised when I finally got my passport for the Preserve Circuit Geocache Challenge. You can find this challenge also on my Geocaching Challenge Index. If you want you can contact them and have a passport mailed to you or you can print the PDF, just go to the website. Get one mailed to you, that is my recommendation. The passport is really nice, it has multiple pages and areas for the stamps.
I have to see how quick I can complete this challenge, because I am not living anymore in the Bay Area. The challenge consists of 22 geocaches which are located in all the different Open Space Preserves.
Upon completion of the challenge you can get a unique Geocoin for your collection. You find all the information and guidelines on their homepage.