Winter skiing is available on Mount Pelion, which has 3 pistes (beginners, improvers and advanced)
It also has a good 5 km cross country course, which is regularly graded. There are views westwards across the Aegean to the perfect snowy cone of Mount Athos, the Holy Mountain, and eastwards across the Pagasitic Gulf to Mount Parnassus, home of the Ancient Muses.
The Alpine-style village of Hania, a short drive from the pistes, has ski shops and kit for hire, and also good places for lunch, outdoors in the sunshine or indoors by a log fire. Good snow, usually, from late December to March. 45 mins by car.
Ski in the morning. Swim in the afternoon.
The sheltered waters of the Pagasitic Gulf are significantly warmer than the rest of the Mediterranean and mid winter water temperatures are often no colder than the English Channel in August! Winter swimming is popular amongst the locals who boast that you can ski in the morning and swim in the afternoon.