9 challenges
National parks
No. 01
Balkans National Parks Passport
Balkans, Southeastern Europe · 56 parks
No. 02
West Coast National Parks
California, Oregon, Washington, and Nevada, United States · 14 parks
No. 03
Rocky Mountain National Parks
Colorado, Wyoming, and Montana, United States · 7 parks
No. 04
Island and Tropical National Parks
Hawaii, US Virgin Islands, and American Samoa, United States · 3 parks
No. 05
Eastern and Heartland National Parks
Eastern and Midwestern United States · 18 parks
No. 06
Desert Southwest National Parks
Arizona, Utah, New Mexico, and Texas, United States · 12 parks
No. 07
Alaska National Parks
Alaska, United States · 7 parks
No. 08
Europe National Parks Passport
Europe · 21 parks
No. 09
National Parks Passport
USA · 63 parks