Is that a phrase you have? Or is it just native to British shores?
This is Deptford Creek in south London, and the River Ravensbourne runs through it....across the creek is world-famous Greenwich. When the conservators arrived, they removed 800 shopping trolleys...but then discovered the fish count dropped dramatically...a rather more prosaic version of when fish colonise shipwrecks. Anyway, at low-tide you can wade through the mud and water to see birds, fish, crabs, flora...and all sorts of rubbish