Off the coast of Mexico, Isla Cozumel’s new biosphere reserve protects the second-largest reef system in the world, the city of San Miguel, and nearly 40 archaeological sites. The reserve supports more than 1,000 marine species and about 80,000 residents. Tourism, including cruise visitors, is a major source of local income, and conserving the reef and cultural sites helps sustain both biodiversity and the island’s economy.