A gulf has a number of definitions: > a portion of the sea, that is almost surrounded by land except one narrow opening (What is a Gulf?) or > A gulf landform is the sea or ocean that reaches into land. read more
For example, the Persian Gulf is narrowly fit in between the Arabian Peninsula and Iran. At the same time, it feeds into the Arabian Sea. The difference between the two is that the narrow and encased gulf feeds into the wide sea. read more