Laird Hamilton, post-feminist, period scientist and shark behaviour expert, appears to have a really great understanding of how menstruation works, what it's like, and how women manage their flow while surfing. He also makes a compelling argument for why women should be kicked out of lineups (at least once a month, but I'm guessing he'd prefer more often) - they attract sharks.
'The biggest, most common reason to be bitten is a woman with her period. Which people don't, you know, they don't even think about that. Uh, obviously if a woman has her period then there's a certain amount of blood in the water. So, but...'
Laird, mate, if I was bleeding that badly, that I was leaking through all and any of the period products I was using and thus onto my clothes and swimmers, I would likely be in a bunch of pain and thus home in bed. Honestly.
The community members of the wonderful Surf Feminism Facebook page* (where I found the original Mpora link to this video) had some more great links to share on the topic of periods, surfing and sharks.
Mother Jones: Do menstruating women attract sharks?
Cooler: Is it dangerous to go surfing on your period?
*FYI, it's a closed group, so shitty people can be ejected. Yay!