A 19-year-old Kentucky girl mysteriously vanished while partying in a bikini on a boat at a local lake, triggering a massive land and water search, according to reports.

Marly Kinney was partying on a pontoon boat with at least 10 friends on Grayson Lake in Carter County Wednesday afternoon when she went overboard to use the bathroom, with the group not initially realizing she was missing, the US Sun reported.

Authorities said the bikini-clad teen was last seen around 4 p.m. Wednesday, with her friends unable to say exactly where on the lake she jumped off the vessel.

The Kentucky Department of Fish and Wildlife Resources said crews have been combing the lake and nearby rails in the eastern Kentucky reserve since Kinney vanished, WSAZ reported.

Lt. Chris Mulholland told the outlet authorities have deployed sonar, K-9 teams and heat-seeking drones in the hunt for the missing teen.

Investigators have released few details as the search continues, while Kinney’s family is pleading for anyone with information to come forward.

“My little cousin is missing,” Sinclaire Marie posted on Instagram Thursday, sharing a homemade missing-person poster.

“If anyone in the Grayson/Ashland/Morehead area have any information please share. Please share this to raise awareness.”

The flyer includes a photo of Kinney and other personal details, urging residents to contact the Carter County Sheriff’s Office with information – but the agency said it is not involved in the investigation.

The department encouraged anyone with information to contact fish and wildlife officials and state police.

“The missing young lady from Grayson Lake, the flyers that are being posted on Facebook has our administrative number on it and the office closes at 4 pm,” the Carter County Sheriff’s Office wrote on Facebook Thursday.

“Kentucky State Police and Kentucky Fish and Wildlife are heading the search. If you have information about this case please notify one of these agencies. We want to ensure any relevant information is received to these agencies promptly.”

The Kentucky Department of Fish and Wildlife Resources and Kentucky State Police did not immediately respond to The Post’s request for comment.

Kinney is described as 5-foot-5, about 125 pounds, with black hair, according to the US Sun. 

She was reportedly last seen wearing a pink, orange and white bikini.