The fireboat was called to the South Bank on Saturday morning when a wooden beam on the river wall caught fire.
Fire engines and the fireboat from Lambeth tackled the blaze just upstream of Blackfriars Bridge.
Tourists and Londoners out for a stroll on the Thames Path gathered to watch the fire crews in action.
One theory is that the fire could have been started by a dropped cigarette.
For the latest local news and events direct to your inbox every Monday, you need our weekly email newsletter SE1 Direct.
7,000+ locals read it every week. Can you afford to miss out?
Read the latest issue before signing up