I'd imagine two or even four divers taking each kid in between them. I assume there's a line, so no one is navigating and the route is fully supplied with any additional air needed. People go on intro dives all the time where an instructor does everything. Obviously the element of the long and narrow passages makes things a lot more difficult but it's doable. You just take your time. This completely unknown new technology seems riskier to me... Full face dive masks take most of the "tricky" don't breath in through the nose out of the equation. I'm a sport diver.
That said, there's always some people who "lose it" during a dive course or even newly certified divers. Though I've yet to hear of anyone who decides to stop breathing air and opt for water, usually they bolt to the top, which isn't an option here. That risk can be mitigated by doing "pool" dives right where the kid are and perhaps short stays in the adjacent cave areas. Maybe some relaxing music can be played as well... Another possibility is adding some "rest stop" by creating air pockets along the way.
They wouldn't need to swim. They would be pushed/towed and/or pulling on a rope. Diving isn't like swimming- the hardest part of swimming is staying on the surface and being able to breath. When you're diving you're just floating there and you have air. Divers typically use fins for propulsion which is quite different than swimming.
In many Asian cultures, swimming is discouraged, parents think it will increase chance of their kids drowning.
Drowning is the leading cause of death of young people in Thailand.
At a pool under a waterfall in Thailand last year I saw a bunch of young people trying to swim. No one wanted to be the first in. Some were plainly terrified. Water was waist deep only! Quite a sight.
In general swimming is not particularly popular in Thailand. Dark skin complexion is seen as something for the poor or uncultured (foreigners generally excluded), and that tends to go along with swimming. This is why you can find more than a few local hotels that will have pools built under natural shade. That way you can swim without being in the sun, even though it's something the vast majority of their target clientele would not want! It's also why you might see a Thai fully dressed while swimming at the beach or a pool. It's not about modesty - it's about avoiding the tan!
If you are poor living away from the beach, it's perfectly natural that you spend your entire childhood without even seeing the beach let alone learning how to swim. Thailand is not an island.
I live in a landlocked country and nearly everyone I know can swim. People usually swim in public pools, lakes or ponds. Swimming is also very often part of the PE middle school curriculum here.
Good of your country. Many cities in SE Asia have none of three. If you are in upper middle class, you can afford private swimming pool membership. Less then .1% schools have swimming pool. Rivers are polluted enough and have no infrastructure in place for swimmers.
That said, there's always some people who "lose it" during a dive course or even newly certified divers. Though I've yet to hear of anyone who decides to stop breathing air and opt for water, usually they bolt to the top, which isn't an option here. That risk can be mitigated by doing "pool" dives right where the kid are and perhaps short stays in the adjacent cave areas. Maybe some relaxing music can be played as well... Another possibility is adding some "rest stop" by creating air pockets along the way.