The mountains and hills of England comprise very different kinds of terrain, from a mountain range which reaches almost 1,000 metres (3,300 feet) high, to several smaller areas of lower mountains, foothills and sea cliffs. Most of the major upland areas have been designated as Areas of Outstanding Natural Beauty (AONB) or national parks. The highest and most extensive areas are in the north and west (including south-west), while the midlands, south-east and east of the country tend to be low-lying.