I owned a blue water capable sailboat for 14 years.
The sharks I've seen in the ocean, blue's, mako's and the like - all known to bite a chunk out of you - swim with the top 1/3 or so of their
vertical tail fin out of the water.
No tail fin seen in the video, so I'm calling BS.
Even Holywood screws this one up.
You can tell porpoise by their horizontal tail and the little fact that it doesn't come out of the water when they're swimming.
The fact that porpoise are air breathers and positively buoyant to an extent means a small amount of the top part of their bodies is a little bit out
of the water in the upper vertical fin area.
I note too that the vertical fin in the video was at the same depth throughout the film.
