Ancient Greek boats and ships
Because Greece was so mountainous, and every place in Greece was so close to the sea, a lot of people in Greece used boats to get from one place to another, even starting as early as the Stone Age. Greek people used boats to fish, and to trade with other places, and also to sail to other cities and fight them and take their stuff. They had different kinds of boats for all these things - small rowboats for fishing, and big trading ships, and fast warships. By the 600s BC, the Greeks were among the best sailors in the Mediterranean Sea (along with the Phoenicians).
To find out more about Greek ships and boats, check out these books from Amazon.com or from your library:
Ships and Seamanship in the Ancient World, by Lionel Casson (1971).
The Ancient Mariners, by Lionel Casson (2nd edition 1991).