From 1969 to 1972, the US Pacific Fleet's Antisubmarine Warfare Force conducted a series of experiments exploring a new approach to antisubmarine warfare that emphasized dispersion, deception and emission control. These experiments, known as the UPTIDE series, explored new operational concepts, identified and developed promising new technologies, and generated a wealth of operationally accurate data that reshaped the Navy's antisubmarine warfare strategy. Because of its imaginative conceptualization, unscripted conduct and rigorous analysis, the UPTIDE series was described by many participants and observers as a model for naval experimentation. Six characteristics appear to have been instrumental to UPTIDE's success: a focus on process versus outcomes; an emphasis on realism; a balance between experimentation and operational responsibilities; a long-term iterative approach; the information flow regarding the experiments both within and outside the Navy; and the backing of senior leadership. Project UPTIDE suggests that military experimentation is most fruitful when it is a focused yet flexible search for opportunity.