Investigations following a report of a missing canoeist are continuing despite a search failing to find anyone.
South Wales Police said it found "relevant sports clothing" but have received no missing person reports.
The hunt for the canoeist began after they were seen in water near Taff's Well, north of Cardiff, shortly before 10:00 BST on Tuesday.
A search for them and another person, reported going into the River Taff the same morning, resumed on Wednesday.
Police have appealed for anyone with a canoe who had been in the river but had got out safely to contact them.
They also released a photograph of equipment found during the search and asked if it was possible the owner could have been mistaken for someone in the water in difficulty earlier in the day.
A South Wales Police spokesman said: "We are now urging those further afield who know of someone who has travelled to south Wales and may have taken part in water sports - but has not made contact or returned home - to come forward.
"Anyone who recognises the recovered items or who was in the River Taff yesterday and may have been mistaken for having got in to difficulty, is also asked to get in touch."
The other person, a man, was reported being in the river at Taff Embankment in Cardiff city centre at 08:40 BST on Tuesday.
There has been no update on the search for him.
The fire service said it assisted with Wednesday's search.
Matt Jones, group manager at South Wales Fire and Rescue, told BBC Radio Wales Breakfast: "Extensive searches were carried out yesterday (Tuesday) at both incidents and tragically no information has been found so far, but again we continue to search and today will see us continuing to support any activity that goes on to search these areas for signs of life or recovery of any evidence or equipment."
Asked whether emergency services were certain the two people had actually been in the water, Mr Jones said: "Both incidents were taken on witness accounts. Members of the public have phoned in being concerned for life.
"We can't be 100% certain that, certainly with the River Taff incident with the canoeist, that someone was in the river."