The SM1500 (4.2/50) introduced by Fibercore Ltd. is a highly bend-insensitive ultralow-profile single-mode fiber for use in fiber optic hydrophones to provide security for harbors, naval bases, oil refineries and other coastal installations. The strength of the 50-µm reduced-diameter fiber has been proof-tested at up to 3% strain per 300 kpsi. It can be used in 10-mm-diameter coils and deployed in towed arrays for oil exploration and marine surveys. The reduction in hydrodynamic drag enables towing by smaller, more cost-effective vessels. Lifetime is predicted to be more than 30 years.