Why was Christopher Columbus was looking for new land?
Christopher Columbus was not looking for a new land. He was looking for a new ROUTE from one known land (Europe) to another known land (the Spice Islands).
The old route was around the tip of Africa and was a very long journey. He reasoned that the world was like a ball not flat, and if he went around the ball in the opposite direction the journey would be shorter. He ran into a couple of continents that were in his way by accident. His mistake was in thinking the ball was smaller than it really was.