We are keen walkers , are there designated footpaths & reasonably marked ,any maps?
I did one cross-island walk last year--port via Chorio to Ellinika beach. I walked according to one of the routes described in Nicksy's reference above (www.cycladen.be/Chorio-SkiadiEngFrame.htm) but then took a 'wrong' turn into a valley and down a long, dry riverbed (the markers seemed to run out) and so missed the Skiadi. With a bit of horse sense and trial & error, I got to the beach in the end anyway.
There is a map on the wall of one of the streets in Chorio (can't tell you which one, I'm afraid) which is a replica of the Anavasi map. I had the Terrain/Skai map, which in this case was less than useful because the marked routes are only detailed on the Anavasi map. Get the Anavasi map if you have the choice between the two.
There is not a lot of what you are asking for most Greek islands, particularly for little visited islands like Kimolos.
I had to make any hikes up on the spot and just head out, only a vague map. One south coast wander went past Aliki and ended up an unnamed west coast beach opposite a small island. Another I ended up in Goupa, east of Chora. There were no markers at all anywhere when I went.
There are number of routes, about 6 detailed on Google Earth/Maps.
In the Google Earth desktop application in the layers Menu on the left tick Gallery > Wikiloc Then click on the marker to get to display the route.
You can obviously then print out a custom aerial view/map as required.
You can use this in conjunction with the reference mentioned in the other posts.Edited: 17 April 2017, 03:07