The shadow plane is a distorted reflection of the material plane. Where there is live and light on the material plane, there is destruction, (un-)death and darkness on the shadow plane. Oceans might be bottemless pits, deserts blacks seas and cities only ruins with walking undead and other unholy creatures. I suggest a challenge to map a region on the material (normal) plane (or grap something you've already done?) and remap it on the shadow plane. Things can get really rough and ugly there and even the distances don't have to agree. I'd really like to see some interpretations of this topic.