Traveling North on the Nile: The ancient Egyptians used the current in the Nile River to travel south to north easily. The Nile River flows south to north, and ends at the Mediterranean Sea. Add steering oars, and suddenly travel south to north was even easier.
Traveling South on the Nile: It was not as easy to travel on the Nile from north to south. Fighting the current with oars took great strength. One day, a clever ancient Egyptian noticed that the winds mostly blew north to south. He invented a square sail to catch the wind. The sail was probably made out of linen. It was attached to a pole that acted as a mast. The pole was attached to a boat. Since the Nile is pretty straight and mostly calm, the ancient Egyptians did not need fancy sails of different shapes to catch the wind. They just needed to catch it. The square sail worked very well.
Ancient Egyptian hieroglyphics use a picture of a boat with its sails down to signify traveling north, because to travel north, they used the current and oars. A picture of a boat with its sails up signify traveling south.
Barks: Traveling by boat was so common and normal to the ancient Egyptians that they even had their Sun God travel around by boat. When a boat was used by an ancient Egyptian god, the boat was called a bark.
Trade: Boats, although common, were not used that much to travel beyond the Nile River. Unlike the ancient Greeks who traveled happily all over the Mediterranean Sea, when ancient Egyptians traders entered the Mediterranean, they stayed close to the coastline wherever they went.