The south coast of the sea is heavily indented , and includes the Gulf of Izmit ( Turkish : İzmit Körfezi ) , the Gulf of Gemlik ( Turkish : Gemlik Körfezi ) Gulf of Bandırma ( Turkish : Bandırma Körfezi ) and the Gulf of Erdek ( Turkish : Erdek Körfezi ) .
The south coast of the sea includes the Gulf of Izmit , the Gulf of Gemlik and the Gulf of Erdek .