San Diego (/ˌsæn diˈeɪɡoʊ/ SAN dee-AY-goh, Spanish: [san ˈdjeɣo]; Spanish for 'Saint Didacus') is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States and the seat of San Diego County, the fifth most populous county in the United States, with 3,338,330 estimated residents as of 2019. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches and parks, long association with the United States Navy, and recent emergence as a healthcare and biotechnology development center. San Diego is the second largest city in the state of California, after Los Angeles.
Chengmai County is located in the northwest of Hainan Island, the county around the Beibu Gulf Urban agglomeration, adjacent to Haikou, the provincial capital. It has been bought for more than two thousand years since the first year of Yuan Feng of the Western Han Dynasty (110 BC). It is one of the three famous historical cities of Hainan during the Western Han Dynasty (that is, hawksbill turtle, purple shellfish and chicory). The county has a population of about 590000 people, with a land area of 2076 square kilometers and a sea area of 1100 square kilometers. Haiyu Central, West Route, West Ring Island Expressway, Middle Route Expressway, Round City Expressway, Yue-Hai Railway and West Ring High-speed Rail all pass through the territory. Chengmai County has successively won more than 60 national honors, such as "hometown of Longevity in the World", "famous Green County in China", "Best Leisure Tourism County in China", "demonstration County in the Construction of Beautiful villages in China", and "Ten famous Tourism Counties with Cultural characteristics". March 2017, finalists for "2017"