Massawa or Mitsiwa (/məˈsɑːwə/ mə-SAH-wə) is a port city in the Northern Red Sea region of Eritrea, located on the Red Sea at the northern end of the Gulf of Zula beside the Dahlak Archipelago. It has been a historically important port for many centuries. Massawa has been ruled or occupied by a succession of polities during its history, including the Dahlak Sultanate, the Ottoman Empire, the Khedivate of Egypt and the Kingdom of Italy.

Massawa was the capital of the Italian Colony of Eritrea until the seat of the colonial government was moved to Asmara in 1897.

Massawa has an average temperature of nearly 30 °C (86.0 °F), which is one of the highest experienced in the world, and is "one of the hottest marine coastal areas in the world."

The historical Massawa lies on the islands Basé (with the historical centre) and Taulud (or Tawalut, Tawlud), connected with each other and with the coast by dams. Massawa seems to have emerged as a port sometime between the 8th and 10th centuries, after the decline of the nearby port of Adulis about 50 kilometres (31 mi) to the south. Massawa was known to Arab geographers from an early period. Ya'qubi referred to the Red Sea port in his Kitab al-Buldan as Badi, a corruption of its local Tigre name Base, while al-Masudi spoke of it in 935 as Nase. The nearby Dahlak Archipelago was dominated by Arabs, while the coast of Massawa was then controlled by Beja tribes. With the rise of the Sultanate of Dahlak in the 11th century, Massawa became the main link between the Muslim-dominated Red Sea coast and the Christian highlands. Local tradition speaks of the Seyuma Bahr ("Prefect of the Sea"), an independent ruler of Dahlak and the coastal regions, who controlled the trade routes between Ethiopia and the Arabian Peninsula.

From the 14th century onward, Massawa attracted increased interest from Christian highland rulers. During periods of political consolidation, Ethiopian rulers expanded their influence up to Massawa, competing with the ruler of Dahlak. War songs of Emperor Yeshaq I mention campaigns to Massawa, where he subdued the deputy of Dahlak. Emperor Zara Yaqob, after consolidating control over the nearby highlands, appears to have reached Massawa in the mid-15th century. He fortified the Gerer peninsula, opposite of the island city, according to a chronicle of Addi Néýammén. It is also reported that both Massawa and Dahlak were pillaged by the Abyssinians in 1464/65, during which "the qadi" was killed (likely a powerful chief official of Massawa).

Massawa only irregularly paid tribute to the Abyssinian rulers of the adjacent highlands, such as the Bahr Negash or the governor of the coastal provinces, but it remained connected to the ruler of Dahlak, who himself was a vassal of the Sultan in Aden.

In the struggle for domination of the Red Sea the Portuguese succeeded in establishing a foothold in Massawa (Maçua) and Arkiko in 1513 by Diogo Lopes de Albergaria, a port by which they entered the allied territory of Ethiopia in the fight against the Ottomans. King Manuel I first gave orders for the construction of a fortress that was never built. However, during Portuguese presence, it was lifted as well as the existing cisterns and wells for the Portuguese Navy watery. It was drawn by D. João de Castro in 1541 in his "Roteiro do Mar Roxo" in their route to attack El Tor and Suez. The captain of the Arkiko was the Portuguese Gonçalo Ferreira, second port on the coast that guaranteed the presence and maintenance of the Portuguese fleets, whenever the port of Massawa was threatened by the Turkish presence. In 1541 the Adalites ambushed the Portuguese at the Battle of Massawa.

Massawa rose to prominence when it was captured by the Ottoman Empire in 1557. The Ottomans tried to make it the capital of Habesh Eyalet. Under Özdemir Pasha, Ottoman troops then attempted to conquer the rest of Eritrea. Due to resistance as well as sudden and unexpected demands for more, the Ottomans did not conquer the rest of Eritrea. The Ottoman authorities then tried to place the city and its immediate hinterlands under the control of one of the aristocrats of the Balaw people, whom they wanted to appoint "Naib of Massawa" and almost made answerable to the Ottoman governor at Suakin. In the city's administration, the local qadi of the sharia court occupied a powerful position in the region, as documented starting from the 16th century to the 19th century his jurisdiction extended over a wide areas from the Habab in the north to the northern Afar coast. Ottoman interest in the city was revived in the early 19th century, when in 1809 a Turkish governor was appointed, and in 1813–23 an Egyptian one. From then on Ottoman governors were appointed regularly, and the naibs lost a part of their influence.