what is the difference between at the beach & on the beach?

Answer 1

'At the beach' would, I think, take in the immediate surroundings of the beach, including the promenade, if any. There is the added dimension of moving about. I'm often at the beach (five minutes walk away) having a stroll. 'On the beach' has the connotation of someone settling down with all the relevant gear, to enjoy the delights of sand and sea. It is more static.