The foreshore is littered with a range of ancient and modern litter, but the sort of litter that tells us something about the river's history, such as ballast cast off from ancient ships, wooden piles from long demolished piers and constructions, pieces of once jagged glass made smooth by the flowing of the river and a range of other things to be found. Down towards the Oxo Tower and the Southbank Centre there is even a patch of sand where you can often see sand sculptors creating pieces of art daily which will soon be washed away by the rising tides.
This idea should be caveated with an assertion that this is only the sort of thing you should do if you have some understanding of tides, and know what the tide is doing at the time. Your author does not want to be held responsible for drownings. For tide times visit the Port of London authority website here.
If you would prefer a more guided experience, London Walks runs occasional Beachcombing walks along the foreshore. For more information click here.