The 21-m (70-ft) waterfall was easily accessible from the town, even by ladies wearing the large heavy skirts of the time.
One could walk from the town to the waterfall in less than five minutes. 
mnli hypothesis: One could walk from the town to the waterfall in less than five minutes.  premise: The 21-m (70-ft) waterfall was easily accessible from the town, even by ladies wearing the large heavy skirts of the time.