The Sheriff's Office said it was asked for assistance at Doran Beach about 10:12 a.m. by the U.S. Coast Guard.
Another kayaker found the man in the water, face down and wearing a life preserver, and attempted to rescue him, the Sheriff's Office said.
"At this time, it is unclear if the individual experienced a medical emergency or how he came to be in the water," the Sheriff's Office said on social media.
An autopsy will be conducted by the Sheriff's Office Coroner Unit. The man's name, age and place of residence were withheld pending notification of his family.