The P7 pupils from the Model Primary School in Londonderry found the dead man at Magilligan beach during a nature trail outing yesterday morning.
Police confirmed that a body of a man was found at Magilligan Point and that a post-mortem will be carried out to determine the cause of death.
The class of 27 children had been combing the beach in small groups when five of them saw the outline of a body and reported it to their teacher.
School Principal Paul Sheridan said: "A group of five children, three girls and two boys, came across the body," he said.
"The children told their teachers – there were two with them – and the authorities were immediately contacted.
"They saw the body from a short distance away and then they did the right thing by telling their teachers.
"I was contacted at the school and the children then went and had their lunch and came back to school.
"We also contacted all the parents of that class to tell them what had happened.
He said the pupils "deserve much praise for their maturity in this very unfortunate situation".