It happened on Wildwood Lake in Southampton just before 5 p.m. Saturday.
A kayak carrying a man and an 8-year-old boy overturned in the water.
A bystander in another boat rescued the child but was unable to reach the 35-year-old, identified as Adolfo Castro.
The Riverhead Fire Department later pulled his body from the water.
----------
* More Long Island news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube
Submit a tip or story idea to Eyewitness News
Have a breaking news tip or an idea for a story we should cover? Send it to Eyewitness News using the form below. If attaching a video or photo, terms of use apply.