Descending more than 400 feet below the surface of Lake Michigan last weekend, in near-total darkness cut only by the lights on his cameras, John Janzen could just make out the outlines of his quarry.

The Senator, a 121-year-old steel freighter that sank off the coast of Port Washington in 1929, was so heavily encrusted with quagga mussels it appeared covered in fuzz.

Although the ship was discovered four years ago by sonar and explored by remotely operated underwater vessels, the perilous deep-water dive was the first time scuba divers had seen the wreck with their own eyes, a “monumental technical achievement” Janzen said.

“This (was) so far beyond what recreational divers experience ... it’s more like going up into space or something,” said Janzen, of Waunakee, who made two dives to the site with fellow diver John Scoles, of Farmington, Minnesota, on Saturday and Sunday. The depth limit for recreational scuba divers is typically around 130 feet.

The Senator sank on a foggy Halloween morning in 1929, after it collided with the Marquette, an ore carrier, 20 miles off of Port Washington. The newly refurbished Senator, along with nine passengers and about 250 brand new Nash automobiles being transported from Milwaukee to Detroit, “rolled quickly over and sank before its crew had a chance to man the lifeboats,” according to an Associated Press report the next day.

The ship’s remaining 20 passengers were saved by a passing fishing tug and the damaged Marquette, which was dragged back to a port in Milwaukee.

The Senator is now a 400-foot-long mass beached at the bottom of the lake. Janzen said the ship appeared to have taken quite a beating — a large metal radio mast that was once vertical is now bent parallel to the boat, and previous surveys have discovered a large gash in the stern from the collision. Cars not chained inside the ship’s hull have fallen from the boat, sliding into the sand, according to the Wisconsin Shipwrecks website.

The shipwreck was listed in the National Register of Historic Places in 2016, as a “rare example of a nineteenth-century vessel type that was vital to Wisconsin’s economy, the steel bulk freighter,” according to the Wisconsin Historical Society. The ship’s structure incorporates steel arches and a movable water ballast system — rare structural amenities. Its frigid surroundings, coupled with the complete absence of natural light, has made the structure one of Wisconsin’s best-preserved shipwrecks.

Paul Ehorn, a shipwreck hunter from Elgin, Illinois, who discovered the ship’s coordinates, drove the divers to the site both days. Loaded with cameras and extra air cylinders and wearing dry suits to combat the 42-degree water, the divers were able to reach the site in less than 15 minutes.

When they arrived, Janzen and Scoles had only enough time to check out the ship’s bow and the pilot house, about 15 minutes of exploration. The longer divers remain underwater, the longer they must spend decompressing, a slow and arduous process that allows dissolved gases built up in the body when diving under immense pressure to gradually be released. The total dive took a little over two hours.

In order to stay down longer at such low depths, Janzen and Scoles used a piece of technology called a close-circuit rebreather, a device that recycles the user’s breath for unused oxygen content. They also hung several traditional air cylinders on the line they used to hook to the shipwreck, for backup.

Despite the precautions, Janzen said, he was “nervous, apprehensive.”

“I used that (apprehension) to help me prepare, to help me focus and do things correctly,” he said.

Eager to return to the shipwreck, they plan to make the dive again in coming weeks.

Ehorn said the insurance company that owns the ship could attempt to collect the antique cars, though it would purely be a “labor of love” for vehicles that may not be worth much after almost a hundred years underwater. The vehicles are considered the “largest unmodified collection of early Wisconsin-built automobiles known to exist,” according to the Historical Society.

No reward without risk

Janzen, 48, said he and Scoles, 47, an industrial engineer, aren’t “macho thrill seekers” but “technical geeks” who pay attention to the risks, and plan closely for the process.

For Janzen, the thousands of dives he has done in the past have all led up to reaching the Senator — his deepest and most dangerous dive yet. Janzen is a chemist and an engineer, but he finds the job boring compared to diving, which forces him to make crucial decisions.

“I like to do things where my decision matters,” he said. “If I make a mistake, it could be fatal. It’s scary, but it also has a lot of meaning to me. There isn’t much reward without the risk.”

Both divers were motivated by the challenge of becoming pioneers.

“No one else had done it before,” Janzen said.

For now, the crew plans to continue scoping out the site — exploring the wreck and collecting high-quality footage of the ship.

After he found the shipwreck on June 21, 2003, Ehorn, 71, kept the exact coordinates mum. But he had been talking with Janzen and Scoles for years about scoping out the site. Taking the dive was ultimately a matter of “biting the bullet,” Scoles said.

Ehorn, who has either discovered, or help discover about 13 shipwrecks, was finally able to see the pair’s footage on Tuesday night — the clearest shots he has seen of the wreckage over years of surveying the site.

“It’s a nice feeling — it was beautiful.”

[Editor's note: This story has been updated to reflect a correction. The original version misstated the year the the Senator was discovered. Paul Ehorn found the wreck via sonar equipment on June 21, 2003.]