Six fire engines and around 40 firefighters tackled a boat fire underneath the Lea Valley viaduct in Chingford.
A pleasure boat was destroyed. There were no reports of any injuries.
The fire is believed to have been accidental and caused by candles.
A London Fire Brigade spokesperson said: "Candles are one of the most common causes of fire. It’s really important that you never leave a candle unattended and keep them away from anything else that can easily catch alight."
The Brigade’s Control Officers took the first of 10 calls to the fire at 0533 and mobilised crews from Chingford, Walthamstow, Edmonton and Tottenham fire stations to the scene. The fire was under control by 0717.
Top candle safety tips
Keep candles away from curtains, furniture and anything else that can catch fire.
Keep loose clothing and hair away from candles when they are lit.
Always place your candles/tea lights in a suitable fire-resistant candleholder.
Make sure the candleholder holds the candle firmly and is on a flat and stable surface to stop it falling over.