100 to 150 eggs are laid for each female turtle from their offspring so some of their population will survive and reproduce for the next generation.
The turtles are trying to climb up to the surface because they were underground so they need to get out of there before they suffocate underground. The sea turtles gets their genetic variation from their "parents".
The Leatherback sea turtles are trying to find the light and feel the wave frequency to remember where to come back to when their older. Organisms like these produce more young so at least one will survive to pass on their genes, this is called Struggle for Survival and Overproduction.
The Leatherback sea turtles are crawling towards the ocean to find the deepest and darkest parts of the ocean so predators won't eat them. Organisms whose traits are best adapted to the environment to survive and reproduce, this is called Differential Survival and Reproduction.
When their in the ocean they have to move quickly so predators won't eat them. Only one out of thousand survive to make more offspring to reproduce the next generation, which goes through the Change in the Gene Pool.
Once the sea turtles are in the water they will try to survive in anyway possible. The predators will try to find the sea turtles and they will try eat them. Most of the predators will succeed to eat them but only the "dominate" sea turtles will survive.