The territories are scattered about the Pacific Ocean and the Caribbean Sea. At 3.8 million square miles (9.9 million km2)[18] and with over 320 million people, the country is the world's third largest by total area (fourth largest by land area)[fn 2] and the third most populous. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries.[24] The geography and climate of the United States are also extremely diverse, and the country is home to a wide variety of wildlife.[25]