Bay muds occur in bays and estuaries throughout the temperate regions of the world.  In North America, prominent instances are: (a) the Stellwagen Bank formed 16,000 to 9000 BCE by glaciation of Cape Cod Bay in Massachusetts, (b) Florida Bay, (c) in California Morro Bay and San Francisco Bay and (d) Knik & Turnagain Arms in Anchorage, Alaska.  In the United Kingdom large bay mud occurrences are found at Morecambe Bay, Bridgwater Bay and Bristol Bay.  Straddling Denmark, the Netherlands and Germany is the Wadden Sea, a major formation underlain by bay muds.
In Asia the Chongming Dongtan Nature Reserve in Shanghai, China, is an example of a large scale bay mud formation.  The Atlantic coast of Africa holds the Banc dArguin, a World Heritage nature preserve in the country of Mauritania.  Banc dArguin is a vast area underlain by bay mud.