Deep Bay (also known as Hau Hoi Wan) is a bay off the northwest coast of Lau Fau Shan, Yuen Long, Hong Kong. It is surrounded to the north by Shenzhen proper and west by the peninsula of Nantau, China. It is also known as Shenzhen Bay (深圳湾). But the most common name is usually Deep Bay.
The name of Shenzhen Bay came much later, at least after the establishment of Shenzhen Special Economic Zone in 1980. The name is becoming more and more notable after a hotel was named Shenzhen Bay. While the government of Shenzhen uses the name widely, the people and government in Hong Kong continue use the local name (后海灣).
The bay's northern shore used to be lined with marshes. As Shenzhen began to develop into a major urban centre, the northern shoreline was reclaimed to provide land for buildings. Some departments had tried to preserve the endangered environment but mistakenly introduced foreign species of mangrove, which threatened their indigenous counterparts.
The marshes remain largely intact along the southern part of the bay, which is under Hong Kong's jurisdiction. Mai Po is an important habitat for migrating birds in the area. Pools of former fishing farming is another attraction to birds.
As a result, it was harder to migrate to Hong Kong than before and thus many crossed the border illegally. Deep Bay became the main access for illegal immigrants because border controls were harder to enforce at sea. It was relatively easy to cross the bay and there were major roads to the urban centres of Hong Kong. The rural town of Lau Fau Shan was the major landing point.