Banten Bay also known as Bantam Bay is a bay in Banten province, near the north west tip of Java, Indonesia. It is part of the Java Sea and has a total water surface of approximately 150 square kilometres and an average depth of seven metres. It includes marine ecosystems such as seagrass fields, coral reefs and a major international bird sanctuary. The coastal zone, including the nearby cities of Serang and the port of Merak, is undergoing rapid industrialisation.
The bay has been the site of two major naval battles: