A Comprehensive Review of Underwater Implosion: Historical Origins, Emerging Mitigation Strategies, and Future Directions

Abstract

Underwater implosion of submerged structures has been studied for more than a century, yet recent high-profile failures have renewed awareness of the remaining risk in modern undersea systems. As pipelines, AUVs, and deep-sea submersibles operate at greater depths and under cyclic loading, exceeding a structure's critical external pressure can trigger a two-stage implosion process: rapid inward wall collapse, followed by abrupt wall arrest that emits damaging pressure pulses. Several notable implosion disasters in the last two decades have prompted increased interest in understanding and preventing catastrophic failure as well as protecting structures and surrounding environments. This review presents the current state-of-the-art of underwater implosion across experimental, numerical, and analytical domains. Emphasis is placed on how shell shape, geometry, and material govern both collapse dynamics and the emitted pressure pulse. Furthermore, UNDEX initiated implosion, sympathetic structures, and partially or fully confined environments are explored. Finally, damage mitigation techniques, including ring stiffeners, foam fillers, and buckle arrestors are discussed. This understanding of a century of work on mechanics, environments, and mitigation strategies provides a framework for treating implosion as a primary design consideration within the undersea engineering ecosystem rather than an unquantified risk.