Hidden in the northern region of Costa Rica, the Celeste River (Río Celeste) winds through Tenorio Volcano National Park with a color so vivid it seems unreal. The river’s striking turquoise hue is caused by a natural chemical reaction between two mineral-rich streams, Quebrada Agria and Río Buena Vista, which merge at a point known as "El Teñidero." This one-of-a-kind phenomenon creates the illusion that the water has been dyed blue, even though no pigments are present.

Midway between Salzburg and Vienna, Linz boasts beautiful Baroque buildings, including Old Town Hall and the Old Cathedral, Alter Dom.

The bayside town of Soufrière was founded by the French in 1746 and named after nearby sulphur springs. The coastal Pitons provide a scenic backdrop to the south and the island's highest peaks rise above the rainforest just a few miles inland.

Seven miles outside of historic Athens, the Greek coastal city of Piraeus lies upon the sparkling waters of the Aegean Sea and is the largest passenger port in Europe, servicing nearly 20 million passengers per year.

You'll know why picturesque Grenada is known as the "spice island" when you notice the scent of nutmeg, vanilla and cocoa in the air. Grenada's waterfalls, lush rain forests, volcanic crater lake, tiny villages, cocoa, nutmeg and banana plantations, rum distilleries, scenic hiking trips, pristine coral reefs, and hidden-away unspoiled beaches all make Grenada one of the most popular ecotourism destinations for those who like to discover off-the-beaten-track natural beauty and charm.