The boy, who has not been named, died at the Longleat Forest resort in Wiltshire on Saturday afternoon, local newspaper the Wiltshire Times reported.
Eyewitnesses told the paper that the boy was playing in the resort's 'sub-tropical indoor pool area' when he was taken ill.
Other children were believed to be in the swimming area as staff tried to resuscitate the boy.
Center Parks operates five hugely popular holiday resorts for short-breaks across England, with the woodland villages - famous for their tropical pool areas - operating at almost 100 per cent capacity all year round.
Thousands are believed to be staying at Longleat Forest alone as the English summer holidays wind down.
A spokesman from Center Parcs UK told the Huffington Post: “We are deeply saddened by the tragic news that a young guest passed away after becoming unwell whilst at Longleat Forest.
“Our thoughts are with the family at this difficult time. We are continuing to offer our support to the family and to our employees who provided immediate assistance.
“In accordance with the family’s wishes for privacy at this difficult time, we will not be providing any further detail or comment.”