Freediving, Freediving Courses, Equalization, Ear Equalization, Coaching.
no clue what the epiglottis was, or how to do a “K” or “T” lock, yet they managed to do the Frenzel maneuver, which by the way is a bit biased to say that Hermann Frenzel was the one who developed it since the sea nomads have been using it for centuries to dive below 10m. Even Umberto Pelizzari