An Illinois woman is dead and her husband is missing, presumed dead after a diving accident in Lake Michigan off the shore of Milwaukee, officials say. The Coast Guard says Susan and James Winn, both 53, were diving with three others around 17 miles from the shore on Friday, Fox 6 reports. Susan Winn was found unresponsive after coming up from 300 feet rapidly and did not survive, officials say. James Winn never surfaced from the dive and authorities, who called off the search Saturday morning, say he is presumed dead, reports the Milwaukee Journal Sentinel. They were both experienced divers. Coast Guard Lt. Phillip Gurtler says the tragedy should serve as a reminder for people going out on the lake this summer to have a plan in place "that if you don't come back, someone knows where you are and when you should be coming back." (More Wisconsin stories.)