Just started to read Umberto Pelizzari's Manual of Freediving. I couldn't help noticing that on the cover picture, the freediver is hyper extending his head, which really creates lots of resistance. The book specifically stated in multiple places that the head should be aligned with the body, not to look upward or forward, yet the illustration on the cover really gives people the impression that hyper extending of the head is the right way. This seems funny to me.