A 14-year-old boy was taken to hospital after he jumped into Southport's Marine Lake from a bridge.
The teenager dropped into shallow water from the Marine Way Bridge and had to be rescued by emergency services when he injured his leg.
Police, fire and ambulance were all called to the rescue operation.
A large crowd of onlookers gathered across the bridge as crews brought the youth to safety.
He was then taken to Ormskirk Hospital by paramedics for treatment to his injured leg.
A police spokesman said: "We were called there at about 8.25 to reports of a young person who had jumped off into the shallow water.
"Fire service, police and paramedics attended and he was led out to safety."
A spokesman for the ambulance service added: "We attended with an ambulance and rapid response vehicle to reports that there was someone in the water who was injured.
"There was one patient, a male in his teens. They were complaining of a leg injury and we've taken them to hospital."
