A group of around 30 cockle gatherers were cut off from the shore in Morecambe Bay, Lancashire, late on Thursday. Seven were rescued or managed to wade or swim ashore.
Police coordinating the rescue said military helicopters and the coastguard began searching for the group when the alarm was raised after dark on Thursday.
Locals often go out onto the beach to harvest cockles, which live just below the surface of muddy sand and are eaten after being shelled and cooked.
But the tides in the bay are dangerous for those not used to them, especially at night. The incoming sea can sometimes surround the unwary, quickly cutting them off from shore.
Local media reported the Chinese cockle hunters may be migrant workers.