The Applied Physics Laboratory, University of Washington, Seattle, Washington, is awarded a $249,996,414 cost-plus-fixed-fee, indefinite-delivery/indefinite-quantity, contract ceiling increase modification to a previously awarded contract (N00024-21-D-6400) for research, development, engineering, and test and evaluation for Department of Defense (DOD) programs including: experimental oceanography, acoustic propagation, underwater instrumentation and equipment, marine corrosion, acoustic and related systems, simulations and signal processing, mission related and public service oriented research and development. This contract modification also increases the value of the contract option ceiling by $473,998,879 which, if exercised, would bring the cumulative value of this contract to $925,770,891. Work will be performed in Seattle, Washington, and is expected to be completed by October 2025. Funds of multiple different appropriation types and years from program offices and agencies throughout the DOD may be obligated on individual task orders. This contract is awarded pursuant to 10 U.S. Code 3204(a)(3), as implemented in Federal Acquisition Regulation 6.302-3; Industrial mobilization; engineering, developmental, or research capability; or expert services. Naval Sea Systems Command, Washington Navy Yard, D.C., is the contracting activity.