Japan. Because it is completely surrounded by water, life is strongly affected. For example, fish is a focal point for food there. Also, war is heavily influenced in Japan. Planes and ships are required to reach targets in Japan. In addition to the water, it is very mountainous. This increases the hardships in farming. Japan is heavily reliant on rice crops; instead of giving that up, they use a method called terrace farming.
The Rocky Mountains hindered travel to the west in the United States for years. However, today it is well-settled.
The Thames and the Euphrates river basically created the Mesopotamian civilizations.
Look at the earth today, it's filled with influencing geographic features!
Hope this helps!