Sea-turtles at midnight on Neil Island.

The briefing happens at nine in the evening, on plastic chairs, and it is mostly a list of prohibitions. No white light of any kind — not a torch, not a phone screen, not a camera. Stay behind the line the volunteers have drawn in the sand. If a turtle is coming up the beach, you do not move at all; if she is already digging, you may approach to the marked distance and no closer. If she turns around and goes back to the water, that nest is lost, and it is your fault.

There were eleven of us. We walked down at about half past ten with one volunteer carrying a torch with a red filter, which turtles do not see well, and we sat at the top of the beach for an hour and forty minutes and nothing happened at all. This, I was told, is the normal outcome and roughly two nights in three.

Nobody spoke. Nobody used a torch. It is astonishing what a group of strangers will agree to in the dark.

At about ten past midnight a shape came out of the surf about sixty metres down the beach. An olive ridley, which is the smaller of the species that nest here, and the crawl up the sand took her a very long time — perhaps fifteen minutes for forty metres, in a hauling motion that sounds, and I did not expect this, like someone dragging a sack. Nobody spoke. Nobody used a torch. It is astonishing what a group of strangers will agree to in the dark.

The digging took another forty minutes: first the body pit, then the egg chamber, cut precisely with the rear flippers alternating, one and then the other, with a delicacy completely at odds with the rest of the animal. Then she laid, which the volunteer told us can be observed from close range because she is effectively unreachable by anything happening around her at that point. I was two metres away. There were, we were told afterwards, somewhere over a hundred eggs.

Then she covered the nest, and then she did something I had not read about anywhere: she spent another twenty minutes moving around the general area throwing sand, disguising the site over a patch several metres wide. And then she went back down the beach into the water, and it was ten to two in the morning, and the whole thing had taken an hour and forty minutes from the surf to the surf.

The volunteers are with a local group that has been marking nests here since 2014, and they relocate the ones laid below the high water line to a hatchery. They take small groups, they take them rarely, and the protocol is not negotiable — a man on our night who took out a phone was walked back up the beach and that was the end of his evening. I would not have wanted it any other way. What was extended to eleven people that night was an hour of an animal's life that would have happened whether or not we came, and the only thing asked of us was that we make no difference to it whatsoever.