Dodgy legs they certainly look like tadpoles. So it sort of reinforces my thoughts that those pools must be above the high water line.
I have since read up on frogs and salt water, seemingly frogs can't survive for very long in saltwater, because surprising to me, they dehydrate rapidly.
But the photo can't be denied they are defo tadpoles.
I used to have jamjars full of them, and sticklebacks from a quarry pond not too far away from that place. Different time, I now feel very guilty about that and I was very young at the time.