Take only photographs, and drink only tap water.
Bottled water is no friend to environmentalists, who want plastic-encased H20 banned from Yosemite National Park and the Golden Gate National Recreation Area in San Francisco, according to the San Francisco Examiner.
A group called "Think Outside the Bottle" want the two parks -- gems of the national park system and also early examples of federally-protected land -- to join the 14 other parks that already ban the sale of bottled water, the newspaper reported.
Parks like the Grand Canyon in Arizona offer water filling stations. Plastic from water bottles is blamed as a chief producer of avoidable waste.
Plastic water bottles made up "20 percent" of the waste at the Grand Canyon in 2010.