It is about 150km drive with great views and historical places.
HERE is also a file to download.
The caches what you can find on the way:
7. Eleutherna Hellenistic Bridge with a little walk
14. Vrissinas-JS#4 with some hike
16. Retymnon view
17. Rethymno nano
19. Rethymnon walk
23. Polios house
24. Moni Arseniu
25. Fossil bay