That’s a really nice and tight ring (the one knocking down the rocks).. it took me the better part of two weeks to learn how to make them come out close that way consistently, and even then mine only look like his maybe once out of every four or five tries... most of the time they’re a little weaker and more lopsided and die out after a few meters... like the ones in the video someone linked above. The video guy is right.. it just takes a lot of practice. It probably would have taken less time for me (and will take those of you who are going to a pool to try it soon) less time too, because it’s a lot more difficult in a current... in a pool I can make them nice and tight maybe 2 out of every 4 times. No current is definitely the way to learn. Another thing the guy in the video didn’t mention was on scuba you only blow a short “burp” of air out, NOT a continuous breath, and only RIGHT before you do the motion to get the ring.
There’s another way to do it that I haven’t seen anywhere on the internet, with only one hand. I’m still working on getting that one down consistently...you sort of hold your hand in the “stop” signal, fingers closed at the top, completely upright, but with your thumb cocked a little towards the front at the joint, then you have to “push” at the air bubbles coming from your reg (before you do it you have to let some air out of the reg and bat the bubbles around so you have a lot of smaller bubbles to move your hand with). Only it’s a “push” with a small flex at the bottom of your palm, not a straight push. Oh, and if you want, after you break the big bubbles up into small bubbles, you can stick both hands out upside dow flat in the bubble column so they rest on the “top” of your hands, then you can make a smaller ring like the first kind in the video above even like 30 seconds later without having to use your mouth.
Oh, and I can sometimes (still working on this one too) make them another way I’ve never seen online.. with just the tips of your two thumbs. Really really macro level tiny vortex rings. probably not useful for anything except perhaps scaring a Pygmy seahorse with.
I learned all 3 from my last half year trip to the Philippines.. the local DMs can do them all day long... and often do, during safety stops. I’ll get back to practicing them again on Wednesday when I’m back in Puerto Galera for another three months and maybe make some videos showing how it’s done.. everyone I’ve dove with in the US has never seen such a thing before lol.
would deliberately book onto a dive excursion to a shark aggregation site
when she geared up on the boat and brought out her Shark Shield! 
