A barrier would have ruined the feel of the site I reckon.
I have a brother who had a fascination with water at a young age. Dad never wrapped any of us in cotton wool, and that brother quickly learnt the error of his ways

A different but related story - as some people know, when I was little, we used to have an appartment on a Cypriot beach - open our back door, walk through the garden, through the gate, and you were on the sand. Another 30 odd yards, your feet were wet. I was a toddler at the time, but soon learned what my depth was waterwise. Addionally, maybe I was excessively clever or something, but if my parents said no, then I didn't do it :-?. I guess it was because there was no Naughty Step or other such crap back then. If I misbehaved, my arse came in contact with Dad's hand. Or worse if I had been very naughty.
As another aside, I remember Dad teaching one of my brothers to swim. We all went out in the boat (we had a speedboat as well), about 30ryds out, threw him in. He learned to swim PDQ. Wish dad had done the same to me, as I was 10 before I could swim without floats

I do feel some of the modern parenting techniques that parents have to follow (either by law or by peer pressure), such as the reasoning with toddlers, or the Naughty Step are just creating a whole bucket load of problems for later.