The Piraeus is the ancient port of Athens and still functions as the chief exit point from the city by sea for destinations amongst the Aegean Islands and elsewhere in the east Mediterranean. Domestic destinantions include all of the Aegean islands except the Sporades and some smaller Cyclades and Dodecanese isles that require a connection. International destinations (apart from cruise ships) include Cyprus and the Middle East.
Warning: Recently, official spelling changed to Pireas -- and all road signs in Athens and around updated accordingly.
Piraeus occupies a huge territory. Check your gate number  in advance so you know where to go (it may take 15 minutes of driving / 30 minutes of walking to reach one end of the port from the other).
Since privatisation of the Port of Piraeus Authority  passenger facilities have improved greatly. Air conditioned tents have been set up at departure locations around the port and free wi-fi internet access is now available.
Sailings (arrivals and departures) are posted outside the Coast Guard Building at Karaiskaki Square, the main bus terminal for the Piraeus suburbs. Sailings are also available online  from the Ministry of Merchant Marine .
The area can become hectic, especially during the summer period, so allow plenty of time to navigate to the correct departure point.
Most travellers arriving in Piraeus from Athens make use of the very convenient Metro . Line 1 terminates at the Port, from there it's a short walk to the Saronic Gulf ferries, hydrofoils and catamarans, or a free shuttle-bus ride to the ships sailing to Crete and the Dodecanses. Central Cyclades ferries conveniently sail from just across the metro station. Metro ticket costs €1.00 and allows unlimited connections on all modes of transport within 90 minutes.
Direct Airport Express buses  run 24 hours between the port of Piraeus and Athens International Airport . Allow 90 minutes for the trip. The Airport is also accessible via the Metro, with a connection at Monastiraki. Bus tickets to the airport, available from the driver, cost €5.00; Metro tickets to the airport are €6.00.
Other public buses connect Piraeus with its outlying suburbs, the southern coastal zone and with central Athens. Bus and trolley-bus tickets cost €1.00 and are valid for unlimited connections(including metro) within 90 minutes. They must be bought in advance (generally from kiosks or inside metro stations) and validated once on board.
The centre of Piraeus and the Port can be negoatiated easily on foot if you are not carrying luggage. Yellow trolley buses (trolley bus no 20) are useful for the run from the Port to Passalimani and then follow the very scenic route around the hill of Castella, terminating at the Line 1 Metro station of Neon Phaleron (Neo Faliro), near the Peace & Friendship and Karaiskaki Stadiums.
Free shuttle buses inside the Port run from across the Metro Line 1 Terminal Station, around the north side of the port to the ships sailing for Crete, the Eastern Aegean and the Dodecanese.
The most important thing to do is to take a ferry to the Greek Islands. You also can have a nice walk in the Pasalimani/Mikrolimano area and look at many amazing yachts and ships.
Another major option is to take the Metro to various parts of Athens (see map of routes on main Athens page). Cost is very modest, and service is very frequent.
There isn't much to buy in Piraeus. Wait until you get to your destination to begin purchasing souvenirs. However, there are many shops and cafes along the harbor front, especially toward the cruise terminal from and near the Metro station.
Delfino Restaurant 60, Akti Koumoundourou, Mikrolimano, Piraeus, tel. +302104120388. Located in Mikrolimano, a cosy bay with hundreds of sailing boats. Excellent seafood restaurant - try the fresh fish on the grill and fresh lobster with linguini. Warm and profesional service. Amazing the indoor and outdoor areas. For mid/high budgets.
Good cafes are very scarce in the port.
Piraeus is a rather chaotic place with traffic that's horrendous even for Greece. Particular caution should be used when crossing the street, or when walking along the pavement by the ferry quays where cars, taxis, and trucks often drive randomly among the crowds of travelers walking to and from the boats.
Piraeus is a huge port filled with sailors, and parts of it are about as tough as you'd expect such a place to be. The areas right by the ferry quays are safe enough, but avoid wandering around the rest of Piraeus, especially at night, unless you know your way around.
Unlicensed taxi drivers often meet arriving ferries. Unlike in some countries, these taxis have a bad reputation and should not be considered as a cheap alternative to licensed cabs.
Pickpocketing gangs have been reported working on the Piraeus-Airport bus; for a full description see the Athens Stay Safe section.
One scam you may encounter in Piraeus is a rather subtle one. A man will walk up to you while you are waiting with your luggage in line to board a ferry. This gentleman is a consummate actor: though he doesn't actually claim to be working for the boat or port, his demeanor and behavior imply strongly that he is. He'll pick up your luggage, brushing aside any objections, and usher you with it to the head of the line, at which point he'll demand a hefty tip. In one reported case the bite was €7.00 (our respondent decided the performance was worth €2.00)