The two-year-old was playing at the Totalán mountains in Malaga, Spain yesterday when his parents witnessed him fall down the narrow shaft.
The hole, in the area known as Dolmen Cerro de la Corona, had an opening of around 25cm in diameter and is thought to be around 110 meters deep.
About 100 rescuers, including firefighters and police, have so far found a bag of candies which the boy was holding when he disappeared.
The alarm was immediately raised and teams from the fire department, Civil Guard, Local and National Police, emergency health services were all mobilised to the scene.
Since the fall, authorities have lowered a camera into the well but as of yet they have not been able to locate the boy.
They are now considering all potential options to rescue the boy, including digging another hole to access the toddler.