Formed from the confluence of five estuaries, those of the Kent, Keer, Leven, Lune, and Wyre rivers, Morecambe Bay is the largest continuous area of tidal flats in the UK. Broad, shallow, and funnel-shaped, the bay has a large tidal range, of up to 35 ft (10.5 m). During periods of spring tides, the sea can ebb as far as 7 miles (12 km) back from the high-water mark. The flood tide comes up the bay faster than a person can run, and parts of the bay are also affected by quicksand, posing dangers for anyone who does not know the area well.
The bay’s extensive mudflats support a rich and diverse range of invertebrate animals, including cockles and mussels, snails, shrimp, and lugworms, as well as one of the largest populations of shorebirds in the UK. The bay regularly hosts 170,000 wintering waders, with several species present in internationally significant numbers, including oystercatchers, curlews, dunlins, and knots. The tidal flats are surrounded by extensive salt marshes, which make up about 5 percent of the total salt marsh in the UK and support a number of rare plants. Much of this marsh area is grazed by sheep and cattle.
The bay is an important location for commercial fishing; the fish species most commonly caught include bass, cod, whitebait, and plaice. However, Morecambe Bay has not escaped the problems of pollution common to many coastal areas of northwestern Europe. Oil, chemicals, and plastic are among the more common pollutants of this ecosystem.
Morecambe Bay has many rich cockle beds. The cocklers use planks of wood called jumbos to soften the sand, which helps draw the cockles to the surface. Because of the fast-moving tides, cockling has to be carried out with an eye on safety. In February 2004, at least 21 Chinese migrant workers drowned after being cut off by the tides.