Safety investigators have criticised a Tyneside college after a seaside trip last summer nearly ended in tragedy.
The teenagers were airlifted to hospital
Twelve students from Walker Technology College had to be rescued after being swept away and stranded on a sandbar at Druridge Bay in Northumberland.
In a statement on Thursday, the Health and Safety Executive (HSE) blamed a lack of appropriate staff training and planning for the incident last July.
Newcastle City Council said procedures had been tightened in all its schools.
The incident began when some of the youngsters entered the water and got into difficulties while others formed a human chain to try and get them out.
A helicopter and lifeboats were scrambled and several teenagers, aged between 14 and 17, were taken to hospital for checks.
The HSE said a thorough investigation had begun immediately following the incident.
This showed the "underlying causes could be attributed to a lack of appropriate staff training, and the effective planning, organisation and conduct of educational visits".
The HSE statement said: "The school had employed a system for out-of-school visits which followed DfES guidelines, but the investigation revealed failures in the system.
"These failures have been jointly addressed by Newcastle City Council and Walker Technology College, and the local authority has reviewed their procedures across all the schools in their care."
The HSE said it would not be taking any further action but would carry out a follow-up visit to test the effectiveness of the revised procedures.
Newcastle City Council said everyone concerned had cooperated fully with the HSE and it was satisfied with the outcome of the inquiry.
It said in a statement: "This was a distressing incident for everyone involved and we are thankful that all pupils were safely rescued.
"The school had adequate systems in place at the time of the incident.
"The LEA has ensured the implementation of the systems has been tightened across all schools in the city and these will be monitored on a regular basis."