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The Southern Pacific Zone of Costa Rica

By October 12, 2022November 30th, 2022Osa

Hot, humid, and hard to get to…. these are undeniable truths about the southern Pacific zone of Costa Rica. But, hard to get to can be good! And, as is often the case, ones detriments can also be ones strongest attributes. Indeed, it is precisely the conditions of constant warmth and humidity found in lowland tropical rainforests that make them the most biodiverse land-based ecosystems on the planet. Although they cover less than 2 percent of Earth’s surface, rainforests house more than 50 percent of all plants and animals found on land.

The lowland forests surrounding the Golfo Dulce are no exception.

The Osa Peninsula’s geological history makes it home to a nearly unparalleled amount of biodiversity. Once an island floating in the Pacific, the Osa evolved in isolation until it merged with mainland Costa Rica by way of the same fault system that extends to California. Located along the Central American isthmus, Costa Rica itself is a hotspot of biological diversity, as innumerable species poured into the land bridge created when the two American hemispheres joined together. When the Osa Peninsula joined the mix nearly 2 million years ago, the area became a tropical landscape of unprecedented richness. The Peninsula is estimated to house 2.5% of the biodiversity of the entire world – while covering less than a thousandth of a percent of its total surface area – truly earning its title as the most biological intense place on earth.

Piedras Blancas Header 09
Piedras Blancas Header 09

One of the last places in Costa Rica to be settled and still sparsely populated, the Osa is covered almost entirely in magnificent, virgin rainforest extending all the way to the Pacific Ocean. The Osa hosts Corcovado and Piedras Blancas National Parks, as well as the Golfo Dulce Forest Reserve, which makes it the largest track of primary (virgin) rainforest in all of the Pacific coast of Central America. Separating it from the mainland is the Golfo Dulce – one of

only four tropical fjords on the planet. The Golfo Dulce is in fact one of the only place on the globe where populations of both Northern and Southern Humpback whales visit to give birth to their young. The Osa packs an unparalleled amount of land and marine species and diverse ecosystems in an incredibly small area, including:

  • The most significant wetland ecosystem and mangrove forests of Central America
  • The largest remaining tract of lowland rainforest in Pacific Mesoamerica
  • 2-3% of flora found nowhere else in the world
  • 323 endemic species of plants and vertebrates
  • The largest population of scarlet macaws in Central America
  • More than 4,000 vascular plants
  • More than 10,000 insects
  • More than 700 species of trees (which is more than all the Northern temperate regions combined)
  • 463 species of birds
  • 140 mammals, including 25 species of dolphins and whales

4 species of sea turtles