Before 1955-1966, 16 instances of whale entanglement with submarine telegraphic cables were reported in the scientific literature. Here we present new information, derived from global cable fault databases, that reveals an absence of whale entanglements since 1959. This cessation coincided with the transition from telegraphic to coaxial telecommunication cables followed by the change to fiber-optic systems in the 1980s. We propose that entanglements ceased in response to advances in cable design, marine surveying, and cable laying techniques. These changes involved the following: 1) development of torque-balanced cables that were less prone to self-coiling, 2) laying armored cables under slight tension to minimize suspensions and loops, and laying low-torque, nonarmored cables with minimum slack to follow the seabed topography, 3) avoidance of rough topography where suspensions may develop, 4) burial of cables below the seabed on the continental shelf and upper slope to protect against shipping and fishing activities, and 5) use of fault repair procedures that reduce cable slack.