I am an area where water falls down from a high place. What am I?

I am a deep valley with very steep sides. What am I?

I am a low place between mountains. What am I?

I am a large mountain that can erupt. What am I?

I am a large body of water surrounded by land. What am I?

I am raised area of land. What am I?

I am a large flat area of land high above sea level. What am I?

I am a very tall, high place on Earth. What am I?

I am a large body of salt water that surrounds a continent. What am I?

I am a large flowing body of water. What am I?