In Ancient Greece the roads were very hard to travel on since they were very muddy and rocky. The travelers mainly were on these roads to get from place to place while trading their goods in exchange for other goods.
Farming was often difficult since the areas were very small so they barely had room to grow their crops that they needed to stay alive. Another reason why it was hard to farm was because there was hardly and flat grasslands it was mostly mountain ranges and rocky surfaces, which was not good for farming.
Colonies were built for a specific reason, and that reason is that eventually they ragout of space and crops for everyone. The crops were the reason why because they needed them to survive and since there was hardly any room to plant them they clearly did not grow very many.
Merchants used ships for many reasons, but there are basically two main reasons why. One is because they needed to get from place to place when trading, which brings us to the next reason. Carrying goods on the ships was thereupon why they were built, not for speed.