Davy Jones Diving on Gran Caneria has these offers for the 2007/8 low season:

5% off all prebooked dive packages and courses for single divers. 10% off if there are two of you.

20% off courses - For 2 or more divers in a group or family taking the same qualification course the tuition costs are reduced by 20% for the second and successive participant.

Bookings must be made at least 14 days in advance.