The 16-month-old boy, Marcus Pandragon Pierce, was found lying face down in the water by his mother, Thai national Malinda Pierce, 34, after she woke around 7pm.
Mrs Pierce immediately alerted police, who arrived to find the distraught mother holding her son's lifeless body while the father, British national Jass Pierce, 50, sat sobbing nearby.
Investigating officer, Pol Lt. Wuttiwat Liengboonjinda, said there was no evidence of foul play. He believed the toddler had died at least an hour before police arrived on the scene.
Mrs Pierce told police that her husband had gone out to run an errand and had left the door open while she was sleeping.
“I woke up and couldn't see Marcus. I went outside to look for him and found him face down in the pool,” said Mrs Pierce.
Marcus' body was sent to Vachira Hospital for further examination.