By Sea

Costa Rica´s territory became eleven times larger when its tricolored flag was first raised over the peak of Colnett Point in September 1869. The claim to Coco Island, roughly 500 kilometers off shore in the Pacific Ocean, gave this small country of only 51,000 square kilometers an exclusive economic zone of 574,000 square kilometers.

In these vast territorial waters, Costa Rica protects coral reefs, beds of seagrass, a thermal dome, an oceanic trench more than 4,000 meters deep and an underwater mountain range more massive than the Talamanca, Guanacaste and Central Volcanic ranges combined. A chain of underwater volcanoes and mountains some two thousand meters high starts just offshore of Quepos and runs south west towards the Galapagos. Interestingly, Cocos Island is the only visible point of this underwater ridge. This ridge serves as an aquatic highway for juveniles of diverse marine species that enrich the waters of the Eastern Tropical Pacific.

In its deep blue womb, Costa Rica shelters more than 6,700 marine species, 90 of which are unique on the planet. The country is best known to the world for its rainforests, not for its rich marine life which still remains quite unknown and unexplored. The rich marine resources are unexplored even by Ticos (a nickname for Costa Ricans) because these sites are remote and sparsely populated. Among the aquatic wonders is the Thermal Dome of Costa Rica, an oceanic phenomenon caused by the strong winds and ocean currents which creates an upwelling of plankton and an oasis navigated by blue whales, dolphins, whale sharks, and large concentrations of fish and marine mammals. In the Southern Pacific, the Golfo Dulce has once again acquired impressive marine life, thanks to the elimination of trawling and long-line fishing with live bait as far as 20 miles offshore.

Despite its overall small size, Costa Rica has a long Pacific coastline. Some 1,160 kilometers of bays, gulfs, steep topography and two large peninsulas touch the sea. From these landmarks, with more and more frequency, we can observe large marine mammals swimming just off the coast.

In December and January, trade winds cool the waters of Papagayo Bay, causing upwelling: deeper waters rise to the surface, carrying large amounts of nutrients which stimulate an incredible growth of algae as they come into contact with the sunlight. This chain of events creates the opportunity to see huge Humpback Whales in courtship and caring for calves. Those who look carefully also may see aggregations of Devil Rays jumping out of the water, hundreds of dolphins in the Murciélago Islands and occasionally Orcas. These false killer whales are attracted to Guanacaste’s coast by the abundance of rays and whale calves. Every month of the year in Csota Rica, there is a marine spectacle worth watching.


Few people realize that during six or seven months out of the year it is possible to see humpback whales in the Pacific waters of Costa Rica. These tropical latitudes are the southern limit for whales coming from the Arctic and the northern limits for whales coming from the Antarctic. From December through March, and July through September, these migratory whales are temporary residents off Costa Rica’s coast. They travel some 9,000 kilometers to arrive here.

Tourism to observe whales and other species of cetaceans has increased significantly over the last years off Costa Rica’s Pacific coast. Visitors can see mothers with calves, small groups of whales, and solitary males moving near the coast. The whales enter calm bays to give birth, spend the night or just rest after the long journey. With a little luck you may see whales from the beach and nearby hills. Some people, while snorkeling, free diving or scuba diving, hear the mating song of the male humpbacks. Off Costa Rica’s coast are both breeding and mating grounds for these giant creatures.

It’s impossible to say how many whales are actually born in Costa Rica. But boatmen and tour operators who scan the sea in search of whales’ spouts, tail flukes and acrobatic jumps don’t hesitate to claim these animals as national patrimony. They say the whales were “born in Costa Rica” when they spot a calf or a mother showing her newborn how to swim, submerge itself or maneuver its tail and fins.

Whale season begins in late November and early December. Humpback whales coming from California, Canada and even further north begin arriving when the northeast trade winds grow stronger. The whales arrive with the resulting change in oceanic currents. Adults (both males and females) are the first to come via this oceanic route and once they arrive in Costa Rica, they move between Guanacaste and Puntarenas. Several weeks later, pregnant females arrive. These whales possibly bred in these same waters the previous year and then spent the gestation period in their northern feeding areas, where krill is abundant. They tend to travel in small groups accompanied by other females. Younger whales do not travel. They don’t begin migrating until they are nine years old, when they acquire sexual maturity.

Boreal winter stimulates migration, which coincides with the phenomenon of upwelling here in the tropics. This is when the coastal communities of Guanacaste, the Nicoya peninsula and the central Pacific receive these splendid visitors. A few intrepid northern whales go as far south as Manuel Antonio in the central Pacific area, but it is not until July that whales coming from Antarctica arrive in Costa Rican waters at Osa, Golfo Dulce, Drake Bay, Whale Bay and Dominical.

With the help of satellite transmitters, scientists from the Smithsonian Institute for Tropical Research have been able to decipher some of the mysteries of this species’ migration. Their research was focused on humpbacks that migrate to Ecuador. Transmitters placed on the whales’ dorsal fins allowed scientists to determine that lone individuals traveled faster and further from the coast than pregnant females and nursing mothers (young humpbacks nurse for up to twelve months). They travel between 65 and 160 kilometers a day. These females stick closer to the coast to protect their young from killer whales, although they are more exposed to noise pollution and disturbances from humans including fishing and tourist activities.



Uncommon Relatives

Rays and sharks belong to the same group of cartilaginous fish. They appeared on the planet 400 million years apart and took very different evolutionary routes. However, they both visit cleaning stations, which are locations where larger marine life animals gather to have their skin cleaned by smaller fish. The purpose of this common activity is to get rid of parasites and heal wounds. Interestingly, the reproduction of rays and sharks also occurs in very similar ways.

Diving enthusiasts flock to San Pedrillo in the Murciélago Islands to watch cleaning stations in action. Giant oceanic manta rays (Manta birostris) slowly approach as butterfly fish, angelfish and snappers await to remove parasites and particles of debris that have accumulated on their backs. Giant manta rays continue the rhythmic movements of their long fins as they remain for an extended time during a full cleaning service.

Bull sharks are intimidating and elusive. When they go to receive their cleaning session, they slow down somewhat. Butterfly fish and angelfish clean them and heal their wounds in a rapid intervention, moving quickly because the sharks are nervous and hyperactive. The Murciélago Islands are an important mating area for bull sharks. The males bite the females on the neck during copulation, and often lose some of their teeth in the process; the wounds suffered by females are busily healed by surgeon fish. Hammerhead sharks frequent their own cleaning station at Cocos Island, entering a state of relaxation so profound that they even flip belly up while the butterfly and angelfish do their work.

Rays and manta rays seem to be summoned by the trade winds. Because they are filter feeders, the cold water brings perfect conditions for them. In December and February, observers of the ocean’s surface are often surprised when one or two devil rays jump out of the water. Gradually, more and more rays follow in a jumping frenzy, leaping left and right.

Devil rays belong to the Myliobatidae family. In addition to their size, another distinguishing characteristic is their ability to “fly” out of the water. Their acrobatic jumps make them appear suspended in mid-air. It is not clear why they jump out of the water, but many times they surprise boats navigating the coasts of the Pacific northwest at the beginning of the dry season, between December and February.

Marine biologists believe these aerial displays help the rays remove remoras that become stuck to their bodies, to escape predators or to communicate with other schools of rays (with the sound made by their bodies splashing into the water). Other hypotheses suggest that these rays are actually engaging in a courtship display or simply having fun. What is certain is that this multitudinous spectacle of jumping devil rays is one of the most astounding sights offered by the rich and changing marine habitat.

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