Cyprus-Israel Optical System (CIOS) is a submarine telecommunications cable system in the Mediterranean Sea linking Cyprus and Israel.
CIOS has landing points in Ayia Napa (), Cyprus and Nahariya (), Israel].
It has a design transmission capacity of 622 Mbit/s and a total cable length of 250 km. The system was supplied by AT&T Submarine Systems and was the longest non-repeatered commercial system at the time.
Operations began on 11 April 1994.