Traditionally, women make better free divers than men. Women have an extra layer of fat which preserves heat in cold waters and they can hold their breath for longer.
The Ama women of Japan are known for their pearl-diving prowess, and have been recorded diving in Japanese chronicles as early as 300BC. Over centuries these women have developed a unique physiology better suited to the task. The word ama literally means “sea person”.
Incredibly, these women have developed a metabolic tolerance to the cold that allows them to dive for longer. Their body temperature goes as low as 30ºC (86ºF) in winter and remains low throughout the year.
The Ama divers of today will wade into the water, dressed in their white cotton bathing suits, up to 300 yards offshore, with a float attached to a net for collecting the oysters, and dive in the vicinity for 2 ½ hours in the summer and 15 minutes in the winter.