Isla Blanca (left, foreground) and Isla Contoy (right, background), Yucatán Peninsula, Mexico. Isla Blanca, or White Island, is designated as Cancun's northernmost coastal area. As shown in the photograph, it looks like a slender arm that protrudes almost from the tip of the Yucatán Peninsula. On its eastern side, the Caribbean Sea shines with many hues of turquoise and blue. To the west, the Chacmuchuc Lagoon goes on for several kilometers until it fuses with the mainland's mangrove forests. Isla Blanca is a bit of a misnomer, as it is not precisely an island. It is instead a large sandbank of white carbonate sediment. Often during tropical storms or hurricanes, the sea will cross over the narrowest sections, thus creating a momentary island from the remaining exposed area. It was because of these times that the name isla became part of the permanent name.

Isla Contoy serves as a home to Contoy Island National Park, a natural reserve where biologists study whale sharks, manta rays, and other sea creatures. It is located at the confluence of the Caribbean Sea and the Gulf of Mexico and is just 8 km long and 20 m across at its narrowest point. Isla Contoy is one of the most important nesting places of seabirds in the Mexican Caribbean. The island's dense mangroves and lagoons provide ideal shelter for over 170 bird species like brown pelicans, olive cormorants, brown boobies, red flamingos, and white herons. During the winter, over 10,000 birds call the small island home. The island's warm waters also mark the beginning of the Mesoamerican Barrier Reef, the second longest barrier reef system in the world after Australia's Great Barrier Reef. Isla Contoy's marine diversity includes over 240 species of tropical fish and eight species of rays. The park's northern shores also are important nesting grounds for hawksbill, loggerhead, and green turtles in the summer months. Whale sharks, too, are sighted nearby between the months of May and September. The island has been protected from development for over 60 years, a big reason for its amazingly rich ecology today. (Photograph taken in March 2021 by Chris Makowski, Coastal Education and Research Foundation (CERF), Charlotte, North Carolina, USA.)