The Pacific Coral Reef stamps are the sixth in an educational series designed to promote appreciation of North America's major plant and animal communities. The previous issuances in the Nature of America series were the Sonora Desert (1999), Pacific Coast Rain Forest (2000), Great Plains Prairie (2001), Longleaf Pine Forest (2002), and Arctic Tundra (2003). This new issue portrays a typical coral reef near the US territory of Guam.

Coral reefs and their surrounding waters are complex ecosystems supporting thousands of different life forms. But like the biologically rich rain forests of the tropics, they are also fragile realms, sensitive to temperature changes and highly vulnerable to human activities that exploit their resources. Reefs can stretch for miles in the clear, shallow waters of the tropics and subtropics. Built up primarily by coral polyps, tiny organisms that secrete calcium carbonate, these massive structures protect the shores of nearby landmasses from wave-induced erosion while providing food and shelter for countless creatures. In Guam alone, scientists have documented approximately 6,000 marine species, including some 250 coral species.