The gulf closest to zero degrees latitude and longitude (the Equator and Prime Meridian) is the Gulf of Guinea.

Here's why:

* Zero degrees latitude is the Equator, which runs through the middle of the Atlantic Ocean, passing through the Gulf of Guinea.

* Zero degrees longitude is the Prime Meridian, which also runs through the Atlantic Ocean, intersecting the Equator near the west coast of Africa, which is where the Gulf of Guinea is located.

While other gulfs exist near the Equator, they are not as close to both zero degrees latitude and longitude as the Gulf of Guinea.