Papahanaumokuakea Marine National Monument, Hawaii *
* Established by George W. Bush administration; expanded by Obama administration
- Where: Northwestern Hawaiian Islands
- What: 582,578 square miles of marine habitat, centered around 10 islands and atolls
- When: Established June 2006; expanded August 2016
- Why: Created by President George W. Bush in 2006, Papahanaumokuakea was the largest marine sanctuary on Earth at the time. But as ocean conservation grew more popular over the next decade, it slipped to 10th-largest. President Obama quadrupled its size in 2016, turning it into Earth's second-largest protected area of any kind. It provides critical habitat for more than 7,000 species of wildlife, including several endangered animals — such as Hawaiian monk seals, Laysan ducks and sea turtles — as well as the longest-living marine species on Earth, black coral, which can live for 4,500 years. Protecting this much marine habitat also provides a buffer against ocean acidification, boosting the resilience of many species by giving them more space to adapt. Commercial fishing and mining are banned, although the monument still allows some recreational fishing, as well as removal of wildlife for Native Hawaiian cultural practices. The area has deep cultural and historical significance, as much of the surrounding land and water is sacred to Native Hawaiian communities.