The nest housing 79 eggs was located in the Khao Lampi-Hat Thai Muang National Park.
Of the 79 eggs, 42 hatchlings made it to the sea on Saturday morning, while three died and 34 eggs were not fertilised.
National park officials believe the three hatchlings died because they were not able to climb out of their nest, which was about a metre deep into the ground.
The officials also said the eggs hatched six days later than the usual 55 days.
The dead hatchlings and unfertilised eggs have been sent to the Phuket Marine Biological Centre for research.