The U.S. Coast Guard said it was called Friday afternoon to the dive boat about 17 miles off Milwaukee about a woman who was unresponsive after surfacing.
Officials said the woman, identified as 53-year-old Susan Winn, came up about 300 feet rapidly, was unresponsive and did not survive.
Her husband, 53-year-old James Winn, did not resurface from his dive, according to the Milwaukee County Sheriff's Office.
"This person was diving which means they had a buoyancy suit on, which means they may not be floating on the surface but maybe a couple feet under the water at which point it is even harder to find," Coast Guard Lt. Phillip Gurtler told FOX6.
A couple from Illinois died while diving in Lake Michigan off the coast of Wisconsin on Friday, according to officials. (WITI-TV)
Authorities search off the coast of South Milwaukee on Friday night and Saturday morning for Winn before calling off the search around 10:30 a.m. on Saturday. Officials told FOX6 that he is now presumed dead.
One Coast Guard boat, one Coast Guard helicopter and three Milwaukee police units were seen searching for the missing diver.
The boat driver and two other divers on board were not hurt in the incident.
The couple from Kildeer, Illinois were experienced divers, officials told FOX6.
Ben Laurie, 21, encountered a bizarre creature while diving near Cape Brett on New Zealand’s North Island. What he thought was a mysterious sea serpent might in fact be a pyrosome, a floating colony comprising billions of sea squirts.
In the wake of the two deaths, the Coast Guard is reminding those heading out on the lake this summer to have a plan in place when heading out on the water.
"Make sure you have a float plan that if you don't come back, someone knows where you are and when you should be coming back," Gurtler told FOX6.
The deaths are now under investigation by the Milwaukee County Sheriff's Office.
The Associated Press contributed to this report.