Emergency crews continue to scour Sikome Lake for a 29-year-old man who disappeared in the water on Monday afternoon.

Police were called to the popular recreation area at about 4:00 p.m. after witnesses say they saw an inflatable boat with four adults and two children tip over in the water.

Onlookers managed to help them get out of the water but one man went under and failed to resurface.

Police shut the beach down and and a search of the water was initiated.

Crews searched until dark but did not turn up any sign of the missing man.

Fire department divers were back in the water on Tuesday and a number of other resources were called in to assist.

“We did have the CPS helicopter out here this morning, they did a fly-over of the area on scene for about ten to fifteen minutes and again they couldn’t see anything but they could identify where this grass bed was under the water,” said Randy Yeats CFD District Chief.

One of the witnesses was at the water’s edge on Tuesday helping to direct crews to where they saw the man go under.

“It’s a bit of a challenge with the turbidity of the water and the amount of visibility we have under the water and there is also a bed of weeds at the bottom so the guys are pretty much searching by hand," said Yeats. "They can see a little bit but when you get into the grass it’s a little bit more difficult so they want to make sure they are covering all the bases."

Family say the missing man is Ali Shaikh.

Wahid Akhtari is Shaikh's brother-in-law and says the family is coping the best they can and awaiting news from authorities.

“We’re not really sure what happened, we just got called, we had to rush down to the hospital that’s all,” said Akhtari.

He says his young niece was taken to hospital as a precaution and is doing very well. “She’s good. She’s at home now, she is doing very well.”

Ahktari says he thinks there was about five or six people on the raft and that they did not know how to swim.

“We’re just waiting until we get any other updates on what’s going on,” said Akhtari. “Just a difficult time right now.”

Calgary police are also at the scene and say they are conducting a potential sudden death/missing persons investigation.

“At this point in time there’s no belief that there is anything suspicious however we are still investigating the circumstances around this missing person, possible drowning,” said Stephen Johnstone, CPS Detective.

The fire department says it will continue to search with the dive team until the end of shift, which is about 5:30 p.m., and then they will make a decision on whether or not to drain the lake.

"We’re going to continue for the rest of our time period, which would be up until our shift change, and there will be a reevaluation done at that point," said Yeats. "Because it’s a provincial lake, they’ll probably make that decision with advice from the police service and fire department."

“It takes about five days to drain the lake completely and once it is drained it would take a couple of weeks, possibly up to three weeks to refill it again,” said Jill Sawyer from Alberta Parks.

Sawyer says they do not have lifeguards at the lake because of the size and number of people who go there.

“We do post Sikome Lake as not lifeguarded though, because it is such a large facility, it’s over nine acres, and we can have up to 50,000 people here a day,” said Sawyer.

She says they do have aquatic safety specialists at the lake and six were working on Monday.

According to Alberta Parks only one person has drowned at the lake in over 30 years.