The seal population around the Cape and the Islands has rebounded remarkably since the Sea Mammal Protection Act. Seals attract Great Whites, and when they are around the seals get out of the pool.
The aerial video is stunning witness. Watch it. In summer, we often swim amongst these big guys, up to 600 lbs. Not cuz we want to, but because they seem to like to swim over to say hi.
I think the video is Monomoy Island.