This made a surprising click in my head. Some 30 years ago, I saw footage of the Ama-san women diving for pearls and one of them being attacked by a shark. It was on a TV documentary, and the blood spreading on the ocean was a haunting image in my childhood. So when in these Ama-san prayers "rid us from sharks" was repeated, there was a chill in my spine. In that documentary the women were young. Here they are elder.