A boater in a dinghy spotted a man's body floating in Lake Michigan's "Playpen" area on Saturday and alerted authorities.

The body was discovered around 4:30 p.m. as the Chicago Air and Water Show concluded. 

U.S. Coast Guard units monitoring the Playpen arrived at the scene first, and the Chicago Marine Police recovered the body. 

Spencer Williams, 29, was pronounced dead at the scene, the Cook County medical examiner’s office said.

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This is the third serious emergency at the Playpen in one week, the Chicago Tribune reported.

One person was left in critical condition on Wednesday after falling off a boat in the Playpen at around 7:30 p.m. that day. Officials are still looking for a second person.

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And last Saturday, two women were severely injured in a boating accident when they were sucked into a boat’s propeller. One woman's feet were severed in the incident while the other lost part of her hand.

One of the women, 34-year-old Lana Batochi, was floating on an inflatable raft when a yacht went into reverse, sucking her raft into the propeller and cutting off her feet. She had to undergo a double leg amputation.

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Batochi said she felt "unimaginable pain" when the boat's propeller sliced her limbs.

"I thought I was dying," she said in the description of her GoFundMe page. "I fought for my life for seconds which felt like minutes. I began to drown, I couldn't swim. As soon as I had my head above the water, at a distance I saw my husband’s eyes searching for me in a panic. I would never forget his face of pain."