When Stacey Lee Harvey went for a walk near Iluka on the New South Wales north coast on the weekend, she thought she'd stumbled upon sharks caught in a rock pool at low tide. But after taking a closer look, she realised it was dozens of sting rays.

"All I could see was the wings on the sting rays, so I raced over a bit excited," Ms Harvey said.

"I didn't know what to think. It's really not normal to see that many sting rays all in one spot I guess, it's just amazing."

The rays, which come from the same family as sharks, were in shallow water at Woody Head.

Lawrence Orel from National Parks and Wildlife said from the photos they appear to be cownose rays.

He said while it is unusual to see such a large group so close to shore, it is likely they were in the shallow waters to feed.

"Cownose rays can be found in really, really large schools like those pictures show where they're really tightly grouped together and that's part of their process for defence as there's always safety in numbers, but it's also the way that they feed, they feed mostly on shell fish.

"In a large group they collectively make up this very large mass that can often stir up the sand, the sediments on the sea bed where they feed, and they'll find the shell fish that they primarily feed on, and that's very likely what they were doing on that rock shelf."

"I'd expect that with the next high tide they would have moved on."

Ms Harvey captured photos of her boyfriend and his friend wading amongst the rays.

While Mr Orel said they're not usually aggressive unless they feel individually threatened, they can sting.

"They do have a barb, or a spine as it's called, and that does have a venom.

"So maybe if you stepped on one, or tried to grab them, they might use that spine to give you a sting."