Holiday company Center Parcs has been fined £250,000 for failing to ensure the safety of tree-climbers at its Woburn Forest site in Bedfordshire.
It follows an incident in 2015 where a young girl fell between eight and ten feet from a tree and broke her wrist during an organised activity.
A court heard the 8-year-old had been unsupervised when she climbed up a rope ladder.
The company said it was determined to learn from what had happened.
Central Bedfordshire Council prosecuted Center Parcs for failings under the Health and Safety at Work Act.
The firm pleaded guilty and have been fined £250,000 with additional costs of £14,000.