

One adult, one inexperienced child, eyes on them the whole time. That is the whole method, and it is the part people skip.
Go on a calm morning, at a beach that still works if the snorkeling lasts five minutes.

A snorkeler above the reef. Photo: Bridger Bowcutt / Unsplash
If two children are new to it, that is two adults, not one adult moving between them. Put the child in a bright rash guard so you can find them at a glance, and use flotation so they can stop swimming without going under. Stay between them and the open water.
Twenty happy minutes is a successful snorkel with a child. Stop before the cold, the fatigue and the frustration arrive.
If a child is cold, swallowing water, fighting the mask or hanging on you, the snorkel is over. That judgment matters far more than getting everyone another fifty yards along the reef, and making it early is what gets you a second morning.
This is why the beach matters as much as the reef. A child may decide after five minutes that the mask feels weird, and you want to still be somewhere worth spending the day.
Set the rule before you go in, not when a honu appears.
If you see one, you stop, you give it room and you watch. You do not chase it, swim over it or reach for it, and that goes for the adult with the camera as much as the child. Say it on the sand so nobody is negotiating it in the water.
Turtles turn up where they turn up and no trip can promise one. Our guide to where to see turtles on Maui covers where the odds are better.

Green sea turtle over the reef. Photo: Hawaii Tourism Authority (HTA)
Pick the beach that survives a failed snorkel.
In South Maui, Ulua and Mōkapu are the easiest family pair, and Maluaka gives you a good beach and a reef in one place. In West Maui it is Kapalua Bay. We are naming these, not ranking the reefs — that detail lives in our best snorkeling on Maui guide, and the wider family planning lives in our Maui with kids guide.

Maluaka, Mākena. Photo: Hawaii Tourism Authority (HTA)
Family-friendly snorkel boat.
Private family snorkel.
Gear fitting and rental.
Put one adult on each inexperienced child. Swapping between two of them is not supervision.
Dress them in a bright rash guard. You will find a lime-green child in the water in a second and a pale one in ten.
Use flotation even if they can swim. It lets a tired child stop without going under.
Agree the turtle rule on the sand. Nobody negotiates it in the water with a honu in front of them.
Call it at twenty good minutes. Ending on a high is what buys you a second morning.
Do not let pool ability set your expectations. Open water is colder, saltier and moves.
There is no age that works for everyone. Water comfort, swimming ability and willingness to keep the mask on matter far more than the number.
Ulua and Mōkapu on a calm morning, or Maluaka if you want a beach and a reef in the same place.
Kapalua Bay.
Yes for water-confident children who are fine on boats. For younger ones a shore morning is usually better, because you can leave the water whenever you need to.
If you see one, stop, give it room and watch it. Never chase it, swim over it or reach for it.
About twenty good minutes. Stop before the cold and the frustration arrive rather than after.