The Pearl River Delta Metropolitan Region (PRD; ; ) is the low-lying area surrounding the Pearl River estuary, where the Pearl River flows into the South China Sea. It is one of the most densely urbanized regions in the world, and is often considered a megacity. It is now the wealthiest region in South China and one of the wealthiest in the whole of China along with the Yangtze River Delta in East China and Jingjinji in North China. The region's economy is referred to as Pearl River Delta Economic Zone. It is also part of the Guangdong-Hong Kong-Macau Greater Bay Area.