The Dirfys is basically a mountain range in on the Evia island close to Athens. The highest peak on that range is the Delfi with an altitude of 1743 meter. I hiked up this mountain in fall 2018 since I spent some time in that area.
First of all, I met hardly any other people on this trail although it was a sunny Sunday in fall. The trail is well marked and easy to reach via the road that connects the western and eastern part of the island.
After 30 minutes, you will reach the Difys refugio which offers also beds for overnight stays. Afterwards, once you actually start to climb up the mountain, the trail will get steeper and in some parts people tend to say that you even have to use your hands. Further details on the trail can be found on this webpage.
All in all it took me a little bit more than 2 hours to get up to the peak from the car. The view on the peak is nice in case you have good weather. There are also some remnants of a crashed plane.
All in all a nice and short dayhike which could easily be combined with the Agali Gorge Hike - the Beauty of Greece.