Sea turtles normally hatch at night. So I'd plan to visit during a full moon, if you can. That way you will have some natural light to work with. I'd recommend using the slowest shutter speed you can that still gives you a blur free shot, so use Shutter Priority (TV on Canons). Newborn turtles generally move in bursts, so focus your shooting on the ones resting between sprints to the sea. That way you can drop your shutter speed to, say, the 1/20th range and still get a crisp shot that is well exposed during a full moon.

If you are doing this at sunrise, I'd recommend using aperture priority (AV). If you want a lot of detail, a larger f/stop will get you that (say f/12 or f/16). If f/12 is too slow, switch back to shutter priority (TV) and shoot from there until the sun comes up enough for you to move over to aperture priority.

I know most sea turtles are dark in color and most beaches have white to grey sand so you might end up with the turtle underexposed or the sand overexposed. To correct this you can shoot RAW and then, in an editing program such as Lightroom, correct the exposure. Or you can use the Canon's built-in HDR setting to help properly expose your shots. Another option would be to set your metering mode to either point or center weighted. You can also use exposure compensation on your camera to help correct the problem.

If your autofocus has enough light to actually focus without much trouble, use it otherwise, use the manual focus.

Don't use your flash and don't use a flashlight to illuminate them, bright lights will confuse them and make their trek to the sea all that harder.