CHICAGO Olivia Smoliga has competed at the very highest levels of swimming in the most pressure-packed environments the sporting world has to offer.

Even the seasoned Olympian, with a gold and bronze medal to her name, admitted to feeling a slight buzz of nerves as she turned in for the night on Saturday.

Smoliga, hailing from Glenview and an alumna of Glenbrook South High School who competed in two Olympic Games, was among the 300 participants diving into the Chicago River on Sunday morning for a landmark swim. This Chicago River Swim was notable as it was the first sanctioned open-water swim event in the river since 1927.

With no lightning in the area and a water quality test conducted Sunday morning turning out OK, the event was given the go-ahead.

The first competitors began their swim at 7 a.m. Sunday. Smoliga was scheduled to be among the swimmers who began at 8 a.m.

“I’m thrilled to dive into the river. No hesitations at all,” expressed Smoliga, who clinched a gold at the 2016 Rio Olympics and a bronze at the 2020 Tokyo Olympics. “I was a bit jittery going to bed, but watching the first group of 2-mile swimmers leap in got me really excited.”

“I’ve always been drawn to the water. I see any body of water, and I want to be in it. So I really couldn’t pass this up.”

The course

The Chicago River Swim course consists of a half-mile stretch along the river’s main channel, between Wolf Point and the State Street Bridge.

The competition features two swimming distances: a 2-mile stretch and a shorter 1-mile route. All participants had to qualify through previous swim events like triathlons.

The route is delineated with sizable inflatable markers, and lifeguards are strategically stationed along the path. Moreover, during the swim, boats are prohibited from entering the river, a restriction enforced by the Coast Guard.

In the previous year, the swim was relocated to the lakefront following the city’s refusal to issue a permit for the river event, citing concerns over safety and crowding. However, last month, the City Council approved the conduct of this year’s swim in the river.

Organizers were out Friday morning running a safety check and setting up the 1- and 2-mile routes.

Swimmers, at least according to Smoliga, will choose whether to attack the course from a strictly competitive mindset, or to just enjoy some of the scenery.

“I’m looking forward to, if I can, taking a peek of beautiful downtown, maybe doing some backstroke under the bridges,” Smoliga said. “I don’t know if I’m going to be much of a competitor (Sunday).

“I’m not an open-water swimmer, so that competitive juice might fire off. Or I might just enjoy the views all around me.”

The cause

The Chicago River Swim is also a fundraiser for ALS (Lou Gehrig’s Disease) research. A Long Swim, a nonprofit organization founded by open-water swimmer Doug McConnell, is putting on the event.

McConnell has lost his father and a sister to ALS. Some of the money raised at the Chicago River Swim will benefit Northwestern University’s Feinberg School of Medicine.

McConnell told WGN-TV he shed a tear when the first swimmers got into the Chicago River on Sunday morning.

“We’ve been working on this for so many years, and to finally see so many swimmers in the water is such a treat,” he said. “It’s just a dream come true.”

A Long Swim has raised $2.5 million for ALS research to date.

“The ALS researchers over at Northwestern’s med school are superstars, and the progress that they’re making is really remarkable,” McConnell said. “We’re just thrilled to be able to support them.”

Additionally, the Chicago River Swim will raise money for The Salvation Army Croc Center Chicago to help provide swim lessons for kids.

And while all the swimmers probably have different goals in mind Sunday, they’ll all have one thing in common as they navigate the Chicago River Swim course.

They’ll be part of history.

For Smoliga, who said she began training in New Trier about four weeks again and is on track to compete in the 2028 Olympic Games in Los Angeles, it’s a one-of-a-kind swim.

“I’m really excited, and it’s events like these that keep my spirit fresh,” she said.