The gates of the rivers shall be opened, and the palace shall be dissolved.

Wesley's Notes

2:6 The gates - Of the city toward the river. The rivers - Of the Tigris, upon which Nineveh stood. Dissolved - While the Chaldeans besieged Nineveh, a mighty deluge overthrew the walls of Nineveh, by the space of twenty furlongs, through which breach the besiegers made their entrance. Dissolved - As if melted, it shall drop to pieces.

King James Translators' Notes

dissolved: or, molten

Jamieson-Fausset-Brown Bible Commentary

6. The gates of the rivers . opened-The river wall on the Tigris (the west defense of Nineveh) was 4,530 yards long. On the north, south, and east sides, there were large moats, capable of being easily filled with water from the Khosru. Traces of dams ("gates," or sluices) for regulating the supply are still visible, so that the whole city could be surrounded with a water barrier (Na 2:8). Besides, on the east, the weakest side, it was further protected by a lofty double rampart with a moat two hundred feet wide between its two parts, cut in the rocky ground. The moats or canals, flooded by the Ninevites before the siege to repel the foe, were made a dry bed to march into the city, by the foe turning the waters into a different channel: as Cyrus did in the siege of Babylon [Maurer]. In the earlier capture of Nineveh by Arbaces the Mede, and Belesis the Babylonian, Diodorus Siculus, [1.2.80], states that there was an old prophecy that it should not be taken till the river became its enemy; so in the third year of the siege, the river by a flood broke down the walls twenty furlongs, and the king thereupon burnt himself and his palace and all his concubines and wealth together, and the enemy entered by the breach in the wall. Fire and water were doubtless the means of the second destruction here foretold, as of the first.

dissolved-by the inundation [Henderson]. Or, those in the palace shall melt with fear, namely, the king and his nobles [Grotius].

Matthew Henry's Concise Commentary

2:1-10 Nineveh shall not put aside this judgment; there is no counsel or strength against the Lord. God looks upon proud cities, and brings them down. Particular account is given of the terrors wherein the invading enemy shall appear against Nineveh. The empire of Assyria is represented as a queen, about to be led captive to Babylon. Guilt in the conscience fills men with terror in an evil day; and what will treasures or glory do for us in times of distress, or in the day of wrath? Yet for such things how many lose their souls!