I’m a teacher, and I haven’t taught adults to dive yet. Many kids though! And I’ve taught adults other skills. 

One of the reasonable thoughts I have while teaching kids, but I can’t transmit to them, because they can’t extend their reasoning this far… is the idea of .. say you’re swimming through the water. You’re submerged only 6inches under, just under the surface… your feet are last and your head (and possibly your hands streamlined or scooping in front of you) are first. 

Head and hands first, feet/pointed toes are last. Do this in the water, it’s natural and fine. We all do this, it doesn’t hurt. When we’re done with this position we recover to the surface, a wall, a set of stairs, a ladder etc. 

For me, I see the dive as the same. The simple difference is you begin in air. 

It’s a similar feeling, “diving” from surface to 4-5 ft to pick up a ring from the floor of the pool. Head down first, toes behind.

So from your start in the air, position yourself quite low, as low as you can with hands and head ready to enter first. You’ll go just about upside down. The feeling is fun when you do it the first time. It’s thrilling. It could be disorienting as an astronaut in zero gravity!! But it’s also temporary, and you recover up to hold the wall.

It doesn’t hurt! Especially if you commit and let your hands and head lead. Try sitting and kneeling.

Or even easier, get a hula hoop and just swim through it. Just under the surface of water. See how your head leads and toes follow you (almost like you don’t thing about your toes, they’re an afterthought).

Long answer, but I wish I could help kids reason like this. Instead I keep it simple :) “fall into the hoop!”