This is the first time the city of Nineveh is actually named by Nahum as the city that is being invaded in Nahum’s vision.
Nineveh’s reputation as a mighty city included its control of deep water reservoirs. It was also protected by moats formed by the Husur and Tigris Rivers.1 This access to and control of water had played an important part in making it such a formidable city. But now all its water is draining away. Maybe literally because of the floods. The city has become like a pool that is draining away. It is losing all its might as a city as it falls to the invaders.
8 Nineveh is like a pool whose waters run away. “Halt! Halt!” they cry, but none turns back.