0 degrees latitude and 90 degrees west longitude is located in the Atlantic Ocean, specifically in the Caribbean Sea.

Here's why:

* 0 degrees latitude marks the Equator, an imaginary line that circles the Earth horizontally.

* 90 degrees west longitude is a line of longitude that runs north-south through the middle of the Atlantic Ocean, passing through the Caribbean Sea.

Therefore, the point where these two lines intersect is a location in the Caribbean Sea.