The term "narrow seas" refers to the stretch of water situated between two landmasses, and there are a few synonyms that can be used to describe it. One common synonym is "strait", which is a narrow passage of water connecting two larger bodies of water. Another word that can be used is "channel", which refers to a narrow strip of water that connects two large water bodies such as a sea or a bay. Alternately, the term "gut" can be used to describe a narrow and frequently turbulent channel of water that connects two larger bodies of water. All of these synonyms serve to illustrate the idea of a narrow stretch of water that links two larger areas.