Small tank with small child might get through the tight spot... larger tank in other areas... We have to assume SEALS know what they’re doing...
https://www.amazon.com/Spare-Air-3000-Standard-Kit/dp/B071WJ2958
https://www.theguardian.com/world/video/2018/jul/06/headcam-footage-difficult-conditions-divers-thai-cave-video