Known as katuali by the locals, the snakes are a subspecies of sea kraits found only in Niue. Lurking in rock formations of the coral reef 30m below, they need to surface for air then dive back down.
I ask our guide, Crystal, which area the snakes are most likely to hang out in.
She replies, "Behind the boat, as the reef drops away you'll see a ravine. That's where they are."
My fellow snorkellers swim off to the shallow reef near the coast where numerous species of bright and dark reef fish populate the superbly clear water. The fish are more plentiful there as the coral is much closer.
A pod of Spinner dolphins regularly cruises around the island. I have seen them on three occasions only 100m from my resort.
Whales can also be spotted close to shore as the reef drops away sharply to very deep water. But, being wild creatures, their behaviour on any given day cannot be predicted.
Today must be their day of rest as there is no sign of either.
Floating on the surface above Snake Gully, I wait patiently.
Concentrating on regulating my breathing though the snorkel in a weightless state is like a form of meditation. I can still see the bottom 30m below through the deep blue.
I think to myself, "If I drop my camera here there's no way I can retrieve it."
Then I see a writhing form swimming straight up. As the black and white striped snake wriggles and weaves its way to the surface, I tentatively swim to within inches of its tail.
With my heart beating at a hundred miles an hour, I fumble with the camera and quickly take some snaps before it dives again.
Got it! On camera, at least. I feel invincible.
Another one swims up while I'm still checking the playback; it pokes its head above the surface.
I sneak up behind it (I can't tell whether it's male or female, they all look the same). It's longer than the last one. This time I gather the courage to stroke its tail.
Realising I am in its personal space, it suddenly wriggles away and dives to the safety of the reef below.
There is a steady flow of snakes slowly going up and down, about one every half minute.
I find that they are non-aggressive and prefer to swim away from me as if I were the poisonous one.
Crystal says nobody has ever been bitten by them in Niue.
The local boys pick them up and wear them around their necks. I'm not quite game enough for that trick. Maybe next time.
CHECKLIST
Getting there: Air New Zealand runs a twice-weekly service from Auckland to Niue.
Further information: niueisland.com.
Andrew Louis travelled as a guest of Niue Island Tourism.
