Walking and hiking is one of the most popular activities in Crete. Follow the links in this site's navigation for more information.
Some windsurfing and kite surfing in Elafonisi and Falasarna. Palaikastro (at the eastern end of the island) is also popular in summer for windsurfing
You can find water-skiing facilities in some of the larger resorts.
There are a few companies offering scuba diving in Crete. A couple of those operate from Chania and one, Notos Mare, from Hora Sfakion.
There are a few horse riding facilities in West Crete: Zoraïda's horse riding in Georgioupolis, the horse riding centre of Deres located in the hills south of Maleme, Lefkoritis horse riding centre and Alianthos Stables near Plakias
Rock climbing is starting to get popular in Crete. There is even a book describing climbing routes in the region of Chania. You can also read more at Climbing in Crete