The waves around their feet do kinda freak them out and when the water rushes back it makes them almost do a "vertigo" kinda thing. Biscuit was leaning over and had to side step to right himself when the water when back!!!
The very first time I laid eyes on Biscuit was at the beach! The man who trained him was riding him and I barely even registered him other than he was a palomino so he'd been to the beach a few times before I took him. Right after I bought him Barry and I took him to the beach. He was a good boy but we rode where there was little traffic as the road is washed out from a hurricane back in 1980 and no people where down there at the time.
Two weeks later I took him back with a group and he was just fine. Go slow...let him look around - you may have to back him into the water if you want him to experience that. It depends on how the tides are!
As for people...keep a good grip on him if you are unsure of how he will react. We went in December and were riding down the beach and a huge BOOM went off. Some kid blew off a huge firework.
You never know what can go on down at the beach! You may want to be sure and ride with someone who has been there before. Best of luck and can't wait to see your pictures. It is too hot to ride at the beach here in the summer - we ride there in December!!
Any tack is fine - just clean it afterwards - I have biothane now but didn't the times I have been to the beach.