This video has been in existence for a while now, as I received it as an email months ago.
For me, it is unbelievable that these intelligent animals would do this in clear weather and calm seas, with plenty of visibility.
And yet, when the humans pulled them back into deeper water, they just got on with it and moved away.
Apart from like you say, seismic and earthquakes possibly affecting them, I'm probably wrong here, ... but I wonder if they, in this particular case, could be coming into the sandy shallows to remove parasites, or some other reason ?
