Good enough for Wordsworth...

Yordas Cave, Kingsdale, near Ingleton. There's easy access to the main chamber which is 55m x 15m wide, with this 9m waterfall in the next part of the cave called the Chapter House. It's apparently been renowned since the 18th century as a natural curiosity and was a show cave in the 19th century. Wordsworth visited in 1800.