Fire officials said the man was partying when he fell off a jet ski. He was under the water for about 15 minutes when emergency crews pulled him out near the 59th Street Harbor.
The man was transported to the University of Chicago Medical Center, where he later died. The victim has been identified to the Cook County Medical Examiner's Office as 52-year-old James Earl Jefferson.
Officials said he wasn't wearing a life jacket. In a tweet, the fire department urged jet ski users to wear life jackets.
Alert. Please wear life jackets when using a jet ski. The victim just pulled from the harbor fell from a jet ski while partying. He had no flotation gear. Was under over 15 min— Chicago Fire Media (@CFDMedia) July 29, 2018