North Wales is a region of Wales, encompassing its northernmost areas. It borders mid Wales to the south, England to the east, and the Irish Sea to the north and west. The area is highly mountainous and rural, with Snowdonia National Park and the Clwydian Range and Dee Valley, known for its mountains, waterfalls and trails, wholly within the region. Its population is concentrated in the north-east and northern coastal areas, with significant Welsh-speaking populations in its western and rural areas. North Wales is imprecisely defined, lacking any exact definition or administrative structure. It is commonly defined administratively as its six most northern principal areas, but other definitions exist, with Montgomeryshire historically considered to be part of the region.