The children had been at a family gathering when they hopped on their bikes and left. The parents spent more than an hour looking for them.
Other than being a little chilly, the children were fine and required no medical treatment.
However, Mr Ellison said the situation could have been a lot worse.
Parents had to always be vigilant when it came to children, he said.
"They can disappear so quick.
"Parents need to know the risk and how unpredictable that beach can be."
A parent who had taken her children to the Napier pump track labelled the incident as "shocking".
"I just couldn't believe they were unsupervised," she said.
"It's such a dangerous beach anyway, but they also had to cross the road by themselves."
Eastern Region Surf Lifesaving Club support officer Debbie Moodie said the stretch of sea along Marine Pde was not a swimming beach and definitely not for children to be swimming in.
"Because the sand doesn't gradually go out to sea but just drops away steeply you can be at knee level and suddenly have to swim back.
"Children must always swim between the flags and that beach is not safe or monitored," Mrs Moody said.
The beach has a history of unpredictability and near drownings.
In 2013 a 12-year-old boy was saved when rescuers formed a human chain to get him out of the big surf.
Josh McQuoid was walking along the Marine Pde beach splashing about on the edge of the waterline when he was dragged into the sea.
The last fatal drowning at the beach was in 2008 when 5 year-old Jago Hohua Te Rangi Kara, who had been playing in the shingle near the water's edge, was swept out by a large wave.
