Cars were driving alongside what appeared to be a waterfall cascading down from Sardis Road Car Park after flooding in the Welsh town of Pontypridd on Sunday.
The traffic seemed unaffected by the volume of water draining from the car park onto the street below.
People were advised to take extreme caution and never drive or walk through flood waters by Natural Resources Wales Head of Flood and Incident Risk Management Jeremy Parr.
There are currently severe flood and red rain warnings in force from the UK Met Office, with those measures expected to remain in place until Monday.
Storm Dennis followed in the wake of last week's Storm Ciara.