The prominent gulf in the Coastal Plain region is the Gulf of Mexico.

The Gulf of Mexico is prominent in the Coastal Plain region, playing a crucial role in shaping its climate, economy, and ecology. This vast body of water borders several U.S. states, including Texas, Louisiana, Mississippi, Alabama, and Florida, and is known for its warm waters and rich marine biodiversity. The Gulf supports a thriving fishing industry and is vital for shipping and trade. Additionally, its coastal areas are popular for tourism, offering beautiful beaches and recreational activities. The Gulf of Mexico is essential for the region's economy and cultural identity, making it a significant geographical feature of the Coastal Plains.