Rio's physical features are dominated by the Sierra do Mar mountain range, which is cloaked by the Mata Atlantica forest. Mountains plunge into the sea, forests meet the beaches, and cliff faces rise abruptly from the extended lowlands. This combination forms the landscape of rare beauty that has made Rio famous as the Wonderful City 'Cidade Maravilhosa'. It's one of the most densely populated places on earth, with seven million 'Cariocas' indulging in dancing, drinking, beach-going and sunbathing. The low coastline has been deeply altered by years of earthwork and has several offshore islands in the background.