The search for a Toronto filmmaker who went missing while scuba diving in the Florida Keys on Tuesday will continue throughout the night and into tomorrow morning if necessary, the U.S. Coast Guard says.

Rob Stewart, 37, disappeared from the waters near Alligator Reef in Islamorada, Florida. at around 5:13 p.m. Tuesday, shortly after he resurfaced from a deep dive.

The filmmaker’s family has said that he was in the area shooting the sequel to his 2006 documentary ‘Sharkwater’ at the time of his disappearance. The film was to tell the story of the 80 million sharks killed each year for reasons other than the use of their fins.

“We want to make sure we do everything we can to find Mr. Stewart,” U.S. Coast Guard Lieutenant Commander Ryan Kelly told CP24 on Wednesday afternoon. “We have small boats that have GPS as well as search patterns overlays that will allow us to search areas taking into account the drift and the weather as well as the currents that are out there. We will use spotlights and try to saturate the areas where any type of current may have possibly taken him.”

Stewart disappeared after resurfacing from dive

Stewart’s parents both travelled to Florida on Tuesday night upon hearing the news.

Speaking with reporters near the search site, Stewart’s father Brian said that he has been told that his son disappeared shortly after surfacing from a dive with two other people. One of those people “collapsed and fainted” following the dive, Brian Stewart said.

“They came up and the dive master went aboard the boat first and collapsed and fainted. They saw Rob come up right behind him and Rob signaled he was ok. They dealt with the guy there, turned around and Rob was gone,” he said. “They don’t know whether he collapsed or he faded or what but we do know that he is an amazing swimmer, who has done thousands of dives and he knows this, he knows what to do, so if he is awake they will find him.”

Though Stewart has now been missing for 24 hours, Kelly said that the U.S. Coast Guard is continuing to “aggressively” search for him and has brought in resources from Florida state to assist with the search and rescue mission.

Through tears Brian Stewart conceded that “it doesn’t look great” but he said that “we have to believe that he (Rob) is the kind of person who will survive.”

Meanwhile, Stewart’s family and friends back in Toronto say they are just trying to keep their spirits up.

“It would be impossible to be anything other than enormously concerned which is why we are focused on doing as much as possible but that doesn’t mean that we aren’t hopeful,” Stewart’s sister Alexandra told CP24 on Wednesday. “With the strength of his swimming, his ease in the ocean, the excellence of the coast guard and the conditions we are facing in terms of the climate in the water I think we are in as good shape as we can ask for.”

Alexandra Stewart told CP24 that she last spoke to her brother over the phone about 10 days ago.

She said that she is only getting by right now by thinking about what she has to do in the next “half an hour or hour” and not dwelling on the worst case scenario.

“We have heard that people can last more than 72 hours in conditions like this. Rob being so strong and at home in the ocean we feel has every chance of making it past that,” she said.

Friends react to news

Officials with the U.S. Coast Guard have said that the conditions in the area have been “very conducive” to their search.

The U.S. Coast Guard, however, has not offered a timeline for how long they will continue to actively search.

Speaking to CP24 earlier Wednesday, Daily Planet host Ziya Tong, who is a friend of Stewart's, described the filmmaker as a "tremendous human being" who has been a "great change-maker."

"Rob has saved hundreds of thousands, if not millions, of sharks around the world, especially because of his awareness, his messages that he’s been bringing," she said.

Tong added that he was doing deep dives of about 200 feet while in Florida.

She said what gives her hope is that Stewart is a "fantastic diver."

"I know that he is incredibly experienced," she said.