I well remember swimming in Vange Creek and in the side pools the other side of the sea wall. The swimming pool had been closed by then because of a polio scare, and only used to catch eels from the Creek. The side of the Pitsea creek were lined with rubbish lost from the barges that came down from London. There were several very high tides during the 1950s and recall the water being to the top of the wall and escaping through a little gap where the path on top of the wall had made a hollow.
Very easy to get stuck on the wrong side at high tide.
That water must have been bacterial soup, how did we survive?