Colombia is the only country with coastlines on both the North Pacific Ocean and Caribbean Sea, which is situated on the northwest of South America. It shares borders with Panama, Venezuela, Brazil, Ecuador and Peru. Colombia shares maritime limits with Costa Rica, Nicaragua, Honduras, Jamaica, Dominican Republic and Haiti. It is a unitary, constitutional republic comprising thirty-two departments. There are regular international flights into major cities including Bogotá (the capital), Medellín, Cali, Barranquilla, Bucaramanga, Cartagena, Pereira and San Andres Islands. Colombia is one of the best coffee producers to date. Ecologically, Colombia is one of the world's 17 megadiverse countries. It has about 2,000 species of marine fish and is the second most diverse country in freshwater fish. It also has a coastline of over 2900km/1802mi, which include rocky beaches, sandy beaches and cliffs. There is a wide variety of scuba diving sights scattered along the coast. Colombia is one of the world’s scuba diving marvels. The islands of Isla Gorgona, Malpelo Islands, San Andres and Providencia are among the most popular locations for diving. The islands of Malpelo and Gorgona are famous for the encounters with schools of hammerhead sharks and manta rays. But the only way to access Malpelo Island is via Liveaboard trips. Isla Gorgona offers excellent diving conditions. In the waters off the archipelago of San Andres and Providencia concentrates one of the greatest densities of coral worldwide. Many of these areas are Marine protected islands and divers need to be accompanied by a guide (or instructor) to gain access to these areas. It's pretty easy to sigh up for a guided tour given the large amount of diving centers in any major town.