Weihai, formerly Weihaiwei, is a prefecture-level city and major seaport city in the easternmost Shandong province of China. It borders Yanta…Weihai, formerly Weihaiwei, is a prefecture-level city and major seaport city in the easternmost Shandong province of China. It borders Yantai to the west and the Yellow Sea to the east, and is the closest mainland Chinese city to South Korea.