Unusually low water in the Lagan on Wednesday afternoon revealed what people most like to throw in the river - bicycles.
I noticed this on an afternoon stroll in Belfast with my camera.
Other photographers might have been drawn by the wildlife on the newly emerged sandbanks; I had an eye for litter.
And between the Albert Bridge and the Ormeau Road I found 15 bicycles, some of them lying fully exposed, some of them buried deep in the mud.
That walk is one mile long.
Some were children's bikes, some were full-sized road bikes and some were so decayed that it was hard to tell what they had been when brand new or freshly stolen.
There were other items in the water, a couple of shopping trolleys, even a satellite receiver dish for someone's television, but there were more bikes than anything else.
Did people just get fed up with their bikes or grow out of them and throw them into the river?
Were many of them stolen and discarded?
It's impossible to tell why bicycles make up more of the rubbish in our river than any other item, aside perhaps from beer cans and bottles.
Each of them will have cost someone hundreds of pounds. Each will have been loved. Many of them will have been fresh, bright Christmas presents.
Some people are not sentimental about their bikes. They ride them to work because they can't afford a car or public transport and are perhaps glad to be done with them.
Maybe some of those bikes broke down and the owners threw them away rather than take the trouble to fix them.
That seems illogical, given that there is not much that can actually go wrong with a bike.
But there they are, in the mud by the side of the Lagan, usually covered by the water. I have walked that route hundreds of times over the years and have never seen this litter exposed like this by low water, so I made a record of it. Had I walked further along the river, I would no doubt have seen more.