In marine turtles, incubation begins when females lay eggs on sandy beaches. Emergence of newborns from the sand marks the conclusion of a much longer process. At the end of incubation, the amnion ruptures inside the egg, and the chorioallantois moves posterior to the embryo to reveal the head and forelimbs, thus freeing the embryo to pip the shell. The juveniles then slowly move to the surface of the sand. The interval between egg pipping and emergence from the nest is not firmly established. We therefore used a motion detector and temperature dataloggers in five Olive Ridley sea turtle nests to evaluate the time between pipping and emergence. The peak of movement is detected between 2 and 3.7 days before emergence, but the first signs of movements are detected as early as 6.5 days prior to this. No thermal signature of pipping was detected. The proximal and ultimate mechanisms relating to emergence synchrony are discussed in the light of these results.