Marsamxett Harbour, also referred as Marsamuscetto in many ancient documents, is the northern of Valletta's two natural harbours on the island of Malta, separated from the southern one (Grand Harbour) by the Valetta peninsula. To the north it is bounded by Gżira and Sliema as far as Dragut Point and extends inland to Pietà and Msida. It is generally more dedicated to leisure use than is Grand Harbour; there is a large yacht marina at Msida and tourist cruise boats operate from Sliema. Within the harbour and reached by a small bridge from Gzira, Manoel Island houses a yacht yard and the 18th century Fort Manoel.
In 2006, during the Maltese round of the Aero GP series, a collision between two planes above the harbour caused the death of one of the pilots.