The nation's marine sanctuaries range in size from the tiny Monitor Sanctuary, which takes up less than a square mile, to the Florida Keys Sanctuary, which sweeps across 3,696 square miles and encompasses the world's third largest barrier reef. U.S. marine sanctuaries take up about 18,000 square miles. That may sound like a lot of sanctuary miles, but consider that the country claims jurisdiction over water that covers nearly as much area as all 50 states.
Marine sanctuaries make up only half of one percent of the water the U.S. controls.
Protecting ocean life balances delicately with promoting human recreation in marine sanctuaries. The challenge is to protect species whose territories are not only miles wide, but also miles deep. In Yellowstone National Park, the animals may cross the boundaries, but at least the land stays put. In marine sanctuaries, water flows freely out to non-protected ocean and back in again, floating in whatever may have been dumped into unprotected waters. As marine life vies with development, the challenges are likely to grow.