Complex sentence: The North Pennines AONB just north of the Yorkshire Dales rivals the National Park in size and includes some of the Pennines' highest peaks and some of its most isolated and sparsely populated areas.
Split into simpler sentences: The North Pennines AONB just north of the Yorkshire Dales rivals it in size. It includes some of the Pennines' highest peaks and some of its most isolated and sparsely populated areas.