Hundreds of kilometres off the Pacific coast of Costa Rica, through deep open water and along underwater mountain ridges called seamounts, one of the ocean's great wildlife highways has been running invisibly for millions of years. Now, for the first time, scientists have mapped it precisely — and the discovery is transforming how conservationists understand and protect what lives beneath.
On March 12, 2026, the One Ocean Worldwide Coalition (OOWC), working alongside Costa Rica's National System of Conservation Areas (SINAC) and national park rangers, announced the completion of Phase 1 of a comprehensive scientific mission to chart the **Cocos–Osa Swimway**: an underwater migratory corridor connecting Cocos Island National Park — a UNESCO World Heritage Site — with the coastal nursery grounds and feeding habitats of the Osa Peninsula, one of the most biodiverse regions on Earth.
The results, based on a full year of field research from March 2025 to March 2026, confirm what marine biologists had long suspected but never been able to prove: that the open water between these two remarkable ecosystems is not empty space, but a living highway.
**Who Uses This Highway**
Using acoustic tagging, baited remote underwater video stations (BRUVS), photo-identification surveys, and genetic sampling, the research teams tracked marine species making the crossing between Cocos Island and the Osa Peninsula.
The roster of confirmed travellers: - **Tiger sharks** — making long-range migrations across open ocean - **Silky sharks and Galápagos sharks** - **Oceanic manta rays** — gliding silently across hundreds of kilometres - **Sea turtles** — using the corridor to move between nesting and feeding grounds - **Sailfish** — among the fastest fish in the ocean, using the route for feeding migrations - **Juvenile scalloped hammerhead sharks** — born in the sheltered bays of Golfo Dulce, then migrating to Cocos Island as they mature
That last piece is particularly significant. Scientists already knew that Golfo Dulce — a rare tropical fjord on the Osa Peninsula — served as a nursery for juvenile hammerhead sharks. What wasn't known was exactly how those juveniles reached Cocos Island's legendary aggregation sites as adults. The Swimway mapping provides that answer: they follow the seamounts.
**Why It Matters for Conservation**
Cocos Island is widely regarded as one of the most extraordinary diving and wildlife sites in the world. Its waters support massive aggregations of hammerhead sharks, whale sharks, manta rays, dolphins, and sea turtles. It has been a UNESCO World Heritage Site since 1997. But all of that biodiversity depends on animals being able to safely travel to and from the island — and until now, the route they used had no legal protection.
"You can protect the destination, but if the journey is dangerous, you lose the animal anyway," says a senior conservation biologist familiar with the project. "This mapping finally gives us the evidence to protect the entire migratory pathway, not just the endpoints."
The Swimway follows the underwater seamounts and ridges of the Cocos Ridge — a chain of submerged mountains stretching from Costa Rica toward Ecuador. These structures concentrate nutrients, create upwellings, and attract prey fish, making them natural navigation corridors for large predators.
**Part of a Larger Vision**
The Cocos–Osa Swimway is one component of an even larger ambition: the **Cocos–Galápagos Swimway**, a transboundary marine protected area spanning the waters between Costa Rica's Cocos Island and Ecuador's Galápagos Marine Reserve — two of the world's most iconic conservation zones. Costa Rica, Ecuador, Colombia, and Panama are collaborating on the broader initiative.
If realised, this network of protected corridors and marine reserves would create one of the most significant marine conservation achievements in history — safeguarding not just individual sites but the ecological connections between them.
**Phase 2 Is Already Underway**
The OOWC has confirmed that Phase 2 is now active, including expanded acoustic and satellite monitoring, deeper genetic studies, and strengthened international collaboration. The goal: build an evidence base comprehensive enough to support formal legal protection for the Swimway — through Costa Rica's domestic law and through international frameworks including the UN High Seas Treaty, which entered into force in January 2026.
The ocean's great highways are invisible to the naked eye. But they are real, they are used by thousands of animals every year, and — thanks to a team of scientists who spent a year in some of the Pacific's most remote waters — we now know exactly where one of them runs. 🦈🌊
*Sources: Tico Times (March 12, 2026) · One Ocean Worldwide Coalition · Costa Rica SINAC · MigraMar Network · UNESCO World Heritage Committee*
