Shrouded in fog, Rob Heitz swam from Alcatraz Island to the San Francisco shoreline Friday morning, completing a feat few would have thought possible for a man left a quadriplegic after a 2003 boating accident.

“I survived!” Heitz said, just an hour or so after finishing the 65-minute swim.

Family and friends had been following along in a motor boat and were there to greet Heitz, 41, at the finish line.

Heitz, who lives in the West Loop, said the water was as cold as he had expected and “I could barely see the hands in front of my face” — unlike Lake Michigan, where he has been training and where he sometimes sees bicycles, garbage cans and a lamppost on the lake bottom.

“It was a couple of inches of dark green water and then an abyss,” he said.

In 2003, Heitz, then 22, was out on his boss’ boat on Lake Michigan near Racine, Wis. The vessel had just anchored. Heitz, unfamiliar with the spot, dove into water that was only 2 to 3 feet deep, striking his head.

He was at first told he was unlikely to ever walk again. The impact from the dive had shattered one of the vertebrae in Heitz’s neck. The spinal cord had been damaged but not severed. Surgeons fashioned a vertebra from a piece of Heitz’s hipbone and fused two other vertebrae together. Titanium plates and screws hold it all together.

At the Rehabilitation Institute of Chicago, now the Shirley Ryan AbilityLab, he was offered a chance to participate in a study using a robotic device that would eventually retrain his brain and body to walk again.

Heitz went back to college after his accident, taking graduate-level classes in biomedical engineering. He’s a salesman for the company that makes the robotic devices that allowed him to walk again. Four years ago, he started a charity to help pay for the devices so that more people could have access to them.

He began training for his San Francisco Bay swim in January 2021.

Heitz said the Friday swim went as planned, although he had to jump in the water quickly because his team got word a barge would soon be passing through.

“It was just foggy enough to be a bit mysterious and add a little bit to the effect of the experience,” Heitz said.

He said he planned to spend Friday in San Francisco and then head to the California wine country before returning to Chicago.