Nurngost

Nurngost was a guard-fortress of Mordor that lay on the coast of the Sea of Nurnen.

This fortress had a great harbor at its south-east end, for the transporting of goods from Caran (to Nurngost's east) and Thaurband (to its west) into the many roads going into the Plateau of Gorgoroth. Because most of the land of Mordor was desolate, places such as these would have been vital for the maintaining of Sauron's vast armies.

This location does not originate from any map that J.R.R. Tolkien himself created.

External reference

 * www.thelandofshadow.com/ragath-dur-ancient-map-of-mordor/