The 10-year-old child was found unresponsive in the Capel Caravan Park’s pool in Capel Sound about 6.20pm on Friday.
His family is understood to have been sharing a meal nearby while he was swimming.
Paramedics took him to hospital in a critical condition, where he later died, police say.
Peter Nilsson, from the caravan park, said their thoughts were with the boy’s family.
“We have contacted the family directly to express our deepest condolences and to offer any support and assistance that we can immediately and in the coming days,” he said.
Support and professional counselling is being provided for residents, guests and staff after the “distressing swimming pool incident”, while the park assists police.
The full circumstances are not yet known and the park is assisting police.