‘Ice can be very deceiving,’ warns expert after recent deaths across Canada

There are renewed warnings about the dangers of venturing onto thin ice or near bodies of water after several recent incidents where people have drowned in lakes and rivers across Canada.

Four teenagers fell into the Rideau River in south Ottawa on Wednesday night. They'd reportedly been skating and fell through the ice.

Two teens got out of the water and were taken to hospital to be treated for mild hypothermia, while divers recovered the bodies of 17-year-old Ahmed Ahmed and another 16-year-old boy who hasn't yet been named.

The tragedy follows the deaths of a family in Alberta reported missing Christmas Day after going off-roading in Lac Ste. Anne County and the death of a man who fell through the ice on Calgary's Bow River the same day.

The search continues for the body of a four-year-old girl who fell into the Mistassibi River in Quebec while sledding with her mother last Friday.

"Ice can be very deceiving … People are looking at the ice thinking that it's solid when it's not," said Stephanie Bakalar, corporate communications manager with the Lifesaving Society in Ontario.

She said about a third of all drownings in Canada happen between October and May because of thin ice and frigid water.

WATCH | Some of her safety advice:

Bakalar said temperature fluctuations, such as what Ottawa has experienced over the past month, can be especially dangerous.

"Maybe to your eye it looks like it's frozen, but underneath it's likely not. As temperatures go up and down, it'll sort of freeze a little, melt a little, refreeze a little; this results in what we call 'dirty ice' and this is very unsafe," Bakalar said.

She said people should measure the ice's thickness using an auger, a device that allows you to drill down and take a sample core of the ice.

The ice needs to be at least 10 centimetres thick to carry the weight of a single person, she said, and thicker if there are more people.

If you take a car onto the ice, the ice should be at least 20 to 30 centimetres thick.

Unofficial skating rink

The area where the Ottawa teens fell in is near locks on the Rideau River and is a popular skating spot, according to the local councillor.

"Typically, it's used by many residents. We can't always say it's safe, because we don't know," said Rideau-Jock Coun. David Brown.

Brown said, unlike the Rideau Canal, ice on the river isn't monitored or maintained.

On Thursday, Ontario Provincial Police (OPP) also released an advisory with ice safety reminders, encouraging people to pay attention to the look, colour and thickness of the ice before venturing onto it.

They also warned that snow, while often inviting, can make the situation even more precarious.

"Unfortunately, it also covers up the ice, so it makes it harder to look and see what is under it," said Const. Michael Mahon, with the Upper Ottawa Valley OPP.

All in a Day10:08How to steer clear of thin ice this winter

The chief of Ottawa Fire Services and a constable with the Upper Ottawa Valley OPP tell us how to avoid dangerous ice on natural waterways.

Never go in after a person

Bakalar recommends that if someone does fall in, they can either try to shimmy their way back onto the ice on their stomach or get into huddle position: lying on their back with their arms wrapped around their knees, keeping their head above the water while calling for help.

Most importantly, if someone falls through the water don't go after them because you could become another victim, she added.

Instead, try throwing them something that floats or something they can grab onto to help pull them out.