Hi (Again),
I went back and noticed the concerns on the inversion seat. This sounds like the HEED trainer, and it's a "slice o' pie". Very low pressure in the shallow end of the pool. Just do what the instructors tell you to do. Use your tongue on the roof of your mouth to create a positive pressure in your sinuses, and not too much, if any water should get in. The worst thats gonna happen is it might burn a little from the chlorine, but again DO NOT panic, just try and relax...If water goes in your snoot, blow out a little and get that positive pressure going again. Practice in the pool by hanging your calves on the pool deck and then gently lean back until your inverted with your back against the pool bulkhead (doesn't all that nautical talk make you want to pack your sea bags?). Good luck...and RELAX in the water folks.
Regards,
Kaman