Cuba is an archipelago located in the Caribbean Sea at the entrance to the Gulf of Mexico, composed of the main island of Cuba, the Isle of Youth, and over 4,000 cays and islets, covering a total area of around 111,000 square kilometers. Cuba has a tropical climate with warm weather year-round and an average annual temperature of 25 degrees Celsius. Cuba was first encountered by Christopher Columbus in 1492 and gained independence from Spain in the late 19th century after several wars, with its population emerging from a mix of indigenous, Spanish, African, and Chinese peoples. As of 2009, Cuba's population was around 11.2 million inhabitants and its official currency is the Cuban peso.