Dispelling a few myths about Samaria
It seems that most of what has been written about the gorge of Samaria was plagiarized from the same original source. This means that the same errors have been repeated almost everywhere.
Let's put a few things right:
The gorge of Samaria is not 18 km long (the 18 km refers to the distance between the settlement of Omalos on the northern side of the plateau and the village of Agia Roumeli) but is 16 km long, starting at an altitude of 1230m and taking you all the way down to the shores of the Libyan Sea in Agia Roumeli.
The walk through the National Park of Samaria is 13 km but you will have to walk the extra 3 km to Agia Roumeli from the exit of the National Park making it a total of 16 km.
The very narrow passage near the end of the gorge is often called the "Iron Gates". None of the former inhabitants of Samaria know why the place suddenly got this name. They were always known by the locals as "Portes" which means "doors" or "gates", but certainly no "Iron" anywhere!
Samaria is said to be the longest gorge in Europe. Good marketing but not quite the truth: the "gorges du Verdon" in South France are a little over 20 km in length.
Samaria is not always crowded. There may be up to 2000 or more people a day walking through the gorge of Samaria but on many days there are only a few hundreds. Keeping in mind that these people do not start at the same time and most of them walk in only in one direction (down) the number of people you will encounter is much lower and it is quite possible to have the gorge more or less to yourself if you choose your time well (see below 'When is the best time to walk through the gorge?' ).
The infrastructure of the National park of Samaria
The park is supervised by the Department of Forestry and is one of a dozen national parks in Greece. You need to pay an entrance fee of 5 Euro (free to children under 15).
The path is maintained and is substantially better than "normal" mountain paths in Crete.
There are wardens along the way (in radio contact with each other) who will help you in case of trouble or injury.
There is also (in theory) a doctor stationed in the village of Samaria. This has not been the case in the last few years (2009-2014).
There are well-maintained springs on the way so that you do not have to carry much water.
There are toilets in several places and plenty of rubbish bins. You find surprisingly little litter, considering the amount of people passing through every day.
You also get a set of rules aimed at protecting the park and making the experience safe and pleasant for everyone.
The gorge is open only during the day time and if you want to start walking in the afternoon you will only be allowed in up to a certain point. The guards want to make sure that everybody who walks in also gets out before nightfall. This is the reason why they ask you to present your ticket on the way out as it (supposedly) enables them to know if there is anyone still in the park at night.