Samaria Gorge is one of the challenging views to see on Crete. It is fabulous and you really can not show its beauty nor greatness on pictures. It is one of those things you need to experience by going there by your very own little feet. Literally. You can not drive by car there, nor ride by a horse. If you get too exhausted or hurt your leg while hiking through it there are donkeys used as taxis.
Agia Roumeli village and South Cretan Sea. This is the point where you start if you decide to choose the easy way.
It is whole day trip. The coach trip starts at early morning picking up people by certain meeting points (hotels, offices) and reaches the north entrance of the gorge around 12:00. At the south end the boat departure time is around 17:00 so you have plenty or time to walk through. But it is more challenging than at home because it is hot. You will be back at the starting point at late evening / night. Depending of course to it where do you stay.
By buying a local coach trip to Samaria Gorge it was very cost effective, easy and simple. You didn't need to worry about cars or public transport times etc. Everything was arranged ready for you and worked well. You don't need to make the reservation at home. When you are on Crete you notice there are plenty of local travel agencies on the streets selling the trips to many places. Just pick one you desire.
Loutro and then to Sfakia where your bus is already waiting for you. Especially Agia Roumeli and Loutro are perfect locations if you seek a place to escape and hide from busy life and hurries just to be forgotten somewhere and not to be found. Crete is full of secret locations with peace & quiet; go to seek your own one! They know someone may be hiding here in these villages. :)
PS. If you want to see a gorge but not any special one and not so challenging one you have many other opportunities. Crete has plenty of them and to many you can buy a coach trip. Also HopOn HopOff busses at Rethymno offers you a change to see Myli Gorge.