In the proposed Phase I program, Bluefin will prepare and submit a safety data package for high cycle-life, long shelf-life, advanced pressure tolerant lithium polymer (Li-poly) batteries for use in, and from the host vehicles of, the AN/BLQ-11 Long Term Mine Reconnaissance System (An/BLQ-11) through provisional safety approval from NAVSEAs Carderock Division under NAVSEA Technical Manual S9310-AQ-SAF-010 (S9310). In addition to the benefits of high-cycle life and long shelf life, pressure tolerant Li-poly batteries would be superior to alternative energy sources for unmanned underwater vehicles because they are robust, safe, do not require failure-prone, heavy pressure housings, and are orientation agnostic. Advanced pressure tolerant batteries are not currently available because of issues with basic battery chemistry, non-standardized manufacturing methods, undiagnosed failure modes, and the absence of lightweight durable packaging. Leveraging U.S. Navy SBIR funding with Bluefins development efforts, we propose an innovative solution for UUV batteries using commercial Li-poly cells with safe, lightweight packaging and safe "smart battery' electronics. Benefit Major benefits of the Bluefins advanced pressure tolerant Li-poly batteries include: safe battery power through innovative packaging and electronic control, reduced total cost of ownership through extended cycle life, reduced maintenance and improved logistics through reduced parts complexity, improved force effectiveness through common modules/systems and reduced training, and development cost savings through the leveraging of commercial R&D expenditures to improve Navy effectiveness. Keywords pressure-tolerant batteries, lithium polymer batteries, unmanned undersea vehicle, lithium battery safety, UUV, lithium-ion batteries