A search for the boy – who was under the age of 16 was launched after emergency calls at 6.15pm on yesterday. His body was recovered at about 11.30pm.
Superintendent Lee Pache, of Lincolnshire Police, said: “We received a high volume of calls for missing people on the coast yesterday.
“At one point, within two hours, we received 10 calls. All of the those who were reported missing, other than the child who sadly died, were located safe and well.
“Our thoughts are with the boy’s family.”
A spokesman for HM Coastguard, which coordinated the response, said: “An extensive search was carried out by two RNLI lifeboats from Skegness and Mablethorpe, the HM Coastguard helicopter from Humber and Sutton Bridge, and Skegness and Wrangle coastguard rescue teams.
“Lincolnshire Police and East Midlands Ambulance Service were also involved. The missing teenager was found and handed into the care of the East Midlands Ambulance Service.”
The tragedy was confirmed as parts of the UK were bracing for another day of sizzling temperatures ahead of three days of yellow weather warnings for thunderstorms.
An amber weather warning for extreme heat is in place until 11.59pm on Sunday for large parts of the south, east, west, midlands and north of England as temperatures are predicted to rise to 32C.
The Met Office has put the warning in place saying that people could experience “adverse health effects”, such as sunburn or heat exhaustion, and delays to transport during the hot weather.
Meanwhile, over in Scotland and Northern Ireland, a yellow warning for thunderstorms is in place from 9am Sunday to 11.59pm Monday as the north experiences a sweep of heavy rain for the next two days.
The forecaster has warned of flash flooding and power cuts as showers beat down across the two regions.
The warning then spreads to England and Wales on Monday and Tuesday, with just the south west and south east of England facing a third day of yellow warnings on Wednesday until 11.59pm, as the rain eases off elsewhere.
(More to follow)