Annie Lennox's daughter Tali and her artist boyfriend Ian Jones were involved in a kayaking accident in New York's Hudson River on Saturday morning.
Tali, 22, was rescued by a boat after being separated from her partner Jones, 32, but he is still missing.
New York Daily News reports that the couple were paddling near Staatsburg when their tandem kayak capsized.
A passing vessel picked up Tali but Mr Jones remains unaccounted for.
Dutchess County Sheriff's Captain John Watterson told People that the river's strong current and alcohol may have caused the pair to capsize.
"The current in the Hudson River is very strong and we believe the current played a role in the kayak capsizing, and once the two got in the water it was difficult for them to stay together," he said.
More than 50 people were involved in the search for Jones on Saturday but suspended the operation at 5pm when water conditions became too rough.
The search resumed at 7.30am on Sunday and involved Marine patrol and a dive team.
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