Dalianwan Bay is an open bay on the east side of the Liaodong Peninsula of northeastern China. The town of Dalian lies along the western shore of the bay. Its significance is that it is ice-free year-round, while the nearby bay of Niuchwang is closed for four months of the winter.

The bay was the rendezvous point for the British fleet for the 1860 assault on China during the Second Opium War.