asujosh1
Dec - Feb are the coolest months in Cyprus.
If 18 C is too cool then may be Cyprus Winter Sun is not for you.
The temperature can vary +/- 5 C. Yesterday was 22 C.
There are several Dive Schools in Cyprus.
I know that the Western half of the island has a Winter Season, unlike the Eastern half, or at least not as much.
Please visit the link below and click on Activities to a Dive Site link.
Good Luck
Liakada
www.liakada.co.uk/activity