Little Stuart Wilson, six, was on a wake board being towed by a boat when he was struck by a speedboat at Cranfield beach on Bank Holiday Monday, 30 August 2010.
He died at the Royal Victoria Hospital, Belfast days after sustaining serious head injuries.
The young victim, who has a brother and two sisters, had been spending the summer holidays in the area with his family in a caravan.
Damien McCann, 37 and from Sandy Hill in Newry, received nine months imprisonment suspended for three years at Newry Crown Court on Tuesday after pleading guilty to a manslaughter charge.
After the sentencing, the Wilson family issued a statement expressing their devastation over the death of Stuart, but also their relief the court case had ended.
The statement said: "Stuart was a very outgoing child who loved football, outdoor activities and playing with his many friends.
"Nothing can bring Stuart back to us but we hope now that the proper authorities will study the legislation and regulations around maritime activity and support the Maritime and Coast Guard Agency's call for stricter legislation.
It continued: "We would like to thank all of those who have supported us through this lengthy and difficult time."
"Stuart will always be in our thoughts.
"Gone but not forgotten," the statement ended.
Meanwhile, the PSNI and the Maritime and Coastguard Agency (MCA) have issued a reminder to those using coastal waters for recreation to be aware of regulations and use the same care and consideration as on the roads.
Captain Jeremy Smart, the MCA's Head of Enforcement, said: "I would like to express our deepest sympathies to Stuart's family, I know that nothing can compensate for their loss.
"This tragic incident must serve as a reminder to all who use the water for recreational purposes that, similar to using public roads, there are rules that govern how craft are to be driven and exercising common sense, particularly when powerful boats are involved, is essential.
"There are numerous approved training courses available covering different types of craft and levels of competence and we would urge all users to get themselves properly trained," he concluded.
PSNI Sergeant Kelly Anne Warnock, added: "We know that nothing can bring Stuart back but we hope that this case will provide a stark reminder to all that care and attention is needed on the water, as much as on land.
"We would urge everyone who uses the water for recreational purposes to take a moment to ensure that they are knowledgeable of legislation and regulations governing the water before they leave land. They should also exercise extreme care and caution when on the water and be aware of other people in the close vicinity.
"I would also like to thank the Maritime and Coastguard Agency for their support and help during this investigation."