What is longest estuary?

The longest estuary in the world is the Gulf of Mexico. The Gulf of Mexico is a large, semi-enclosed body of water located between the United States, Mexico, and Cuba. It is connected to the Atlantic Ocean by the Straits of Florida. The Gulf of Mexico has a surface area of approximately 1.6 million square kilometers (600,000 square miles). The maximum depth of the Gulf of Mexico is approximately 4,384 meters (14,383 feet).