The researchers know whose nest it is. Each leatherback (I think the other turtles, too) that comes out of the water either has or doesn’t have a chip in her shoulder. When she comes up, the researchers who patrol the beach nightly locate her, scan her chip, measure her carapace length and width, and count her eggs. They also put a thermo-couple (thermometer) in the nest so they can watch the temperature. I think you know why they want to know the temperature. More on this later.
Boil (verb): The term to boil means just that. Think about a pot of boiling water and how the movement of the water is. All of a sudden the hatchlings start digging upward furiously, pushing the sand that is on top of them below them. At once the sand opens up and the babies emerge and start trekking for the water.