Ice shelves extending seven kilometres across Lake Huron's shoreline have developed in southwestern Ontario's northern tip, and municipal officials say they're deadly.

The phenomenon at Sauble Beach draws locals and tourists every year to see the frozen shelf that towers three metres above the waterline and spreads up to 10 times farther from the shoreline.

South Bruce Peninsula Mayor Janice Jackson said the layer of snow resting on the ice can also cover up any holes and cracks that aren't necessarily frozen all the way through.

 "They're quite stunning to look at. People are very curious and they're walking right out to the edge of them," she said. "The problem is there's lots of weak spots and holes that people don't see under a thin layer of snow and they can fall through these holes very easily."

Jackson says the ice shelves have claimed the lives of three people over the last three decades, and they're particularly more dangerous this year, as they have developed over the relatively short span of two weeks.

Ice Shelves

Ice shelves extending seven kilometres across the Huron Lake shoreline have developed in southwestern Ontario’s northern tip, and municipal officials say they’re deadly. (Submitted by Janice Jackson)

Sound the alarm

Jackson took to social media over the weekend to shed light on the dangers of ice shelves through a Facebook status that received up to 1,000 online shares.

The sound of the alarm went off for Jackson after she noticed up to five families on the ice shelves at a time over the holidays.

"There are so many people out on these shelves right now — entire families with their dogs — looking at how amazing [the ice shelves] are, and its really frightening to see them there."

She's warning people to stay off the ice shelves that could easily swallow someone under water, with frigid temperatures making it difficult to reach the surface again.

"People would not be able to hear you calling for help, and it's so cold … you wouldn't last in that frigid water for long," she said.

"Don't go on them at all. Take a look at them. Enjoy them but just don't' walk on the ice shelves."