Damietta is a port in Dumyat, Egypt on the Mediterranean Sea at the Nile delta, about 200 kilometres north of Cairo.

In ancient Egypt the city was known as Tamiat, but it became less important in the Hellenic period after the construction of Alexandria.

Damietta was important in the 12th and 13th centuries during the time of the crusades. In 1169 a fleet from the Kingdom of Jerusalem, with support from the Byzantine Empire, attacked the port, but it was defeated by Saladin.

During preparations for the Fifth Crusade in 1217, it was decided that Damietta should be the focus of attack. Control of Damietta meant control of the Nile, and from there the crusaders believed they would be able to conquer Egypt. From Egypt they could then attack Palestine and recapture Jerusalem. The port was besieged and occupied in 1219, but by 1221 the crusaders had been defeated outside Cairo and driven out of Egypt.

Damietta was also the object of the Seventh Crusade, led by Louis IX of France. His fleet arrived there in 1249 and quickly captured the fort, though he refused to hand it over to the nominal king of Jerusalem, to whom it had been promised during the Fifth Crusade. However, Louis too was eventually defeated in Egypt and was forced to give up the city.

Because of its importance to the Crusaders, the Mameluk Sultan Baibars destroyed the city and rebuilt it with stronger fortifications a few kilometres from the river. Today there is a canal connecting it to the Nile, which has made it an important port once again. The modern city has a population of about 1 million.