The driver of the boat, Matthew Gibson, had no UK-recognised qualification despite having five years' experience as a ski-boat driver. Staff said there was a "lax" attitude to health and safety.
The court was told how parents of some of the children were watching from picnic tables when Mari-Simon fell into the water. Two of the witnesses leapt into the river after failing to get Mr Gibson's attention. The driver later told police he did not see the girl fall in. He said:
I turned the boat around and she went under.
More top news
London singer-songwriter Dua Lipa and Croydon grime artist Stormzy led the charge at the Brit Awards, winning two prizes each.
The awards followed the lead set at the Grammys to show support for the Time's Up movement with artists wearing white roses.
The husband of a British citizen jailed in Iran has delivered letters of support for his wife to the Iranian embassy.