Zona Marina de la Isla Isabel

Zona Marina de la Isla Isabel National Park protects the marine waters surrounding Isla Isabel, a small volcanic island approximately 70 kilometers northwest of San Blas in Nayarit state. ^[1] The marine zone was formally established by presidential decree in 2024, complementing the island national park established in 1980 by extending federal protection to approximately 31,695 hectares of productive reef, open-water, and pelagic habitats in the surrounding sea. ^[2] The marine park designation recognizes that the extraordinary wildlife of Isla Isabel—including blue-footed boobies, olive ridley sea turtles, and a diversity of sharks and rays—depends critically on the health of the surrounding marine ecosystem for food and breeding resources.

The marine zone protects extraordinary wildlife diversity. CONANP documentation records 382 invertebrate species, 14 coral species, 223 fish species, 12 mammal species, and 50 bird species within the protected area. ^[1] Blue-footed boobies (Sula nebouxii), red-footed boobies (Sula sula), and brown boobies plunge-dive for fish in the waters immediately around the island. Whale sharks (Rhincodon typus) are seasonal visitors in the warmer months. Manta rays and mobula rays aggregate seasonally. Olive ridley sea turtles nest on the island beach from June to November. Hammerhead sharks and silky sharks inhabit deeper offshore waters. Humpback whales and whale sharks transit the marine zone seasonally.

The marine ecosystem supports productive tropical Pacific reef communities in the shallower nearshore waters and open-ocean pelagic systems in the surrounding sea. Coral communities include Pocillopora branching corals, encrusting Porites, and 14 coral species in total documented within the marine zone. ^[1] The reef structure provides habitat for moray eels, parrotfish, and diverse reef fish assemblages. Macroalgae including Sargassum, Halimeda, and coralline algae dominate the benthic community. Rhodolith beds (rhodolite algae formations) form important biogenic habitats on the seafloor. ^[2] Phytoplankton blooms driven by coastal upwelling fuel the food chain supporting the island's seabird populations.

The Isla Isabel marine zone encompasses the submerged flanks and surrounding seafloor of the volcanic island, which was formed by Quaternary alkalic basaltic eruptions approximately 3.5 million years ago. The seafloor deepens from approximately 20 meters around the island to over 100 meters a few kilometers offshore. The underwater terrain includes submerged basalt lava formations, rocky reefs, rhodolith beds (red calcareous algae formations), and sandy flats. ^[1] The marine zone is positioned in a highly productive oceanographic transition zone where the California Current brings cooler, nutrient-rich water south and mixes with warmer tropical water, driving the exceptional marine productivity that sustains the island's wildlife.

The marine zone shares the tropical dry climate of the Nayarit Pacific coast. Sea surface temperatures range from 22°C in the coolest months to 30°C during El Niño events. The rainy season from June to October brings warmer water, increased moisture, and occasional tropical storms. The dry season from November to May corresponds to the period of highest marine productivity driven by coastal upwelling. Strong northwest winds drive upwelling along the Nayarit coast in spring, bringing cold, nutrient-rich water to the surface and triggering plankton blooms. Visibility in the marine zone is best during the dry season with 20 to 30 meters underwater clarity.

The waters around Isla Isabel were fished by indigenous communities from the Nayarit coast for centuries, particularly for shark, tuna, and sea turtles. Commercial fishing for sharks and sea turtles intensified in the mid-20th century, significantly reducing populations before the island received protection. Sport fishing vessels from San Blas began targeting large pelagic fish in the 1970s. Diving and snorkeling tourism attracted by the island's renowned wildlife began in the 1990s and has since become the primary human use of the marine zone. The island's scientific research program run by UNAM has monitored marine ecosystems since the 1970s.

The Zona Marina de la Isla Isabel was established as a national park in 2024 to complement the existing Isla Isabel National Park with formal marine protection, providing legal authority to regulate fishing, diving, and navigation within the surrounding 31,695 hectares of ocean. ^[1] WILDCOAST and other conservation organizations had collaborated with local fishing communities and government agencies for years in developing no-fishing zones and community surveillance programs before the formal decree. ^[1] CONANP manages both the island and marine zone as an integrated unit, with ranger patrols covering both the land and sea. The marine zone is coordinated with the broader CONANP Pacific marine protected area network.

Snorkeling and scuba diving in the marine zone are the primary activities, with the richly diverse reef fish assemblages and 223 documented fish species as the signature experience. ^[1] Reef diving reveals Pocillopora corals, parrotfish, and moray eels. Blue-footed booby feeding behavior is visible from the water surface as birds plunge at high speed into the sea. Whale shark snorkeling is offered by San Blas operators when sharks are present. Kayaking around the island perimeter explores the rocky coastline and sea caves. UNAM research station activities occasionally include citizen science involvement.

Access is from San Blas, Nayarit, by chartered panga or larger vessels, a journey of approximately 2.5 to 3 hours depending on sea conditions. No regular ferry operates. The marine zone has no on-water facilities. Landing on the island requires permits from CONANP; visitor numbers are limited to protect nesting seabirds. San Blas town offers simple hotels, restaurants, and boat charter services. The dry season from January to May is best for calm seas and clear water. ^[1] Equipment must be brought from San Blas.

The marine zone protects the productive ocean environment that sustains Isla Isabel's extraordinary wildlife populations. The primary threats are illegal fishing within the protected area and potential oil and chemical spills from vessels transiting nearby commercial shipping lanes. CONANP patrols enforce fishing prohibitions and regulate dive operator behavior. Sea turtle nest protection on the island beach is coordinated with marine monitoring of turtle movement in surrounding waters. The formal declaration of the marine zone enables stronger enforcement action against illegal fishing, which was previously difficult to prosecute without a formal protection decree. ^[1] Microplastic pollution accumulating near the island is an emerging concern. Scientific monitoring of seabird breeding success links marine fish availability with ecosystem health indicators.