I think Ashton gate is at an altitude of -2metres, or 2m below sea level, I am not sure if there are others , but grimsby place used to be basically on the beach!
Of course there would be 'plaice' on the beach in Grimsby - it's a fishing port
Ashton Gate may well be below sea level, but I don't think that's what roo was referring to - our ground is a natural amphitheatre with the playing surface lower than surrounding street levels. Hence below 'ground level'.