All year round, but winter is the most appealing season for European divers because the water temperature is constant and there is no thermocline. The sea ranges from 19ºC in winter to 26ºC in summer (that's 66 to 78ºF), and the difference from 0 to 50 metres (0 to 165 feet) in depth is just one degree. What's more, visibility is usually 20 to 25 metres (65 to 80 feet).