Driving on Pelopennese and Crete

I haven't been to Crete so this technically only applies to the mainland.

Greek roads are pretty good and well marked in English. But have a good map or GPS for navigating in urban areas.

All drivers MUST have an International Driving Permit and in my experience Greek rental agencies DO ask to see it.

Outside of Athens, roads are pretty lightly traveled and drivers are not so insane. In mountains you'll have twisty turns and always use caution as slow vehicles or livestock may be just around the corner. But it was never hair-raising. Always drive along the far right side as the middle of the road is for passing (rural roads can be pretty wide).

Driving in Nafplio is not bad as it's not a huge city but parking can be tough to find along the bay. We parked up the hill closer to our hotel. Ask your hotel for convenient parking nearby and good directions as there are many pedestrian streets.

There is a scenic mountain route from Tripoli to Olympia that I recommend. Doesn't take much longer than the main highway.

Just a bit more about driving in Greece. There are far fewer cars on the roads these days with the economic problems and high prices for gas, That makes it far easier for us to rent a car and drive there.
The advice to stay to the right is the truth. You are expected to drive with your right side tires on the paved shoulder. This makes room for faster cars to pass. You have to be aware not only of what is going on in front of you but also what is happening behind you. The little rental cars in a pinch can get up to 120 km per hour. The locals are in BMW'd Audis and Mercedes and on the big highways will pass you doing over 150. I remember having to pass a slow truck. I checked my rear view mirror, nothing there then looked at the truck started to pull out and a Mercedes went screaming past. They are fast.

You will be on some rural roads getting to Olympia and south Crete. While they are pretty decent two lane highways they go through mountainous or just hilly country. There may not be a paved shoulder but you are still expected to drive over on the right.
More interesting though is the Greek tendency to drive in the middle of the road on blind curves. i am not kidding they all do it so on a curve be prepared to get out of the way. Having said that by the time we were finished our ten day trip I was driving in the middle of the curves as well. It just seemed to be the right thing to do. Because of the hills and curves all this takes place at a very low speed so everyone has time to change course.

Road signs are in Greek but then a couple hundred meters along they are repeated in English.

The tip about having GPS and a good map is correct. Place names in Greece can be spelled in many different ways so you need the map to try to get the correct spelling for the GPS programming and you need the map to double check your progress. There are many places in Greece with the same names. We misprogrammed our GPS several times but by checking the map we were able to correct.

Hopefully after Olympia you will have time to visit Delphi. In my opinion its even better than Olympia.

Olympia Delphi Meteora https://www.flickr.com/photos/stanbr54/sets/72157645469717811/

I forgot Nafplio. We stayed at Agamemnon a couple of years ago. Its a bit tired but it has an excellent location right on the waterfront promenade. Our room had ocean views out to the Bortuzi castle.
There is no parking at the hotel its all reserved down there. The main road that passes behind the hotel has free on street parking. If you can't find a spot there just keep going up the hill. There is a free parking lot up there enough for 20 cars. If you are really stuck keep going up. There is a large lot at the top of the hill but then its a long way back down to the hotel.

here is what you can expect in Nafplio
Nafplio and Peloponnese http://www.flickr.com/photos/stanbr54/sets/72157632094108982/

So much depends on what time of year and where you'll be going for a rental. Late May/early June will still be outside the High Season so there'll be less tourists on the road. As far as Greeks driving they are not your casual-let's-go-for-a-ride types so you should be OK

We didn't rent a car while in Nafplio. We took the bus from Athens to Nafplio and found it to be a perfect way to get there. While in Nafplio we took the bus to go to Epidavrous, Myceanea and Tolo and there are buses to other parts of that area. Obviously a rental will give you more options and freedoms and the traffic should be very tolerable

The road from Athens to Nafplio will start out as a highway then once you take the exit for Nafplio will become a secondary road with a lot less traffic.

There should be ample parking in the New Town of Nafplio but if you are staying in the Old Town you may have to do a little walking but not really that bad.

I've stayed in Chania in western Crete and didn't rent a car. We took to the bus to get to other parts of that area of the island. There is bus service to Heraklion but obviously a rental will give you more options and freedom. I didn't see a whole lot of difficult travel and traffic while in Chania but that was in October when there are less tourists about.

Douglas, Stanbr, Tommyk5: Thank you so much for your replies. It is helpful to know all of these things. One more question please. I've read that it is better not to drive at night. Have you driven at night and why is it better not to drive then? There is an Epidaurus Festival going on while we are there an I was hoping to go see a play in the theatre, but that would mean we'd have to drive back to our hotel, in Napflion, at night.

I haven't driven in Europe, but I believe the recommendation not to drive after dark is based simply on the fact that the accident rate increases when visibility diminishes. Risks are always higher on curvy, mountainous, 2-lane roads as opposed to freeways, and driving those beautiful scenic roads is a major reason why tourists rent cars.

acraven is correct. Driving back from Epidavros in the dark after a full day and an event on unfamiliar roads isn't a good idea. If there is an event there is bound to be bus transportation. Why take the risk?