Black Rock was an area of the undercliff where an outdoor swimming pool used to be, built on a slightly raised platform, dating from the 1930's. Nothing remains of it now, apart from the name ...as it's the last stop on the Volks Railway (a 1.25 mile long scenic railway that opened in 1883 and is still going to this day)...a little further on were the rock pools...an area also known as Black Rock...probably because of the contrast they made with the chalk cliffs...to be honest I'm not sure how the Brighton Marina development from the early '70s has affected this area...but those rock pools must still crop up at low tide :)