This book chapter has consolidated extensive experimental, numerical, and analytical research on ultra-lightweight cement composites (ULCC) and their sustainable, highly ductile and rubberized variants such as ultra lightweight high ductility cement composite (ULHDCC), LC3 based ULCC and rubberized ultra-lightweight cement composites (RULCC), which integrate low content polyethylene fibers (PE) and recycled rubber powder to enhance sustainability, ductility and impact resistance. Alongside their application in steel–concrete composite sandwich systems and advanced composite connectors, these materials form the core focus of the work. Across seven chapters, it demonstrated how novel material formulations and structural innovations can simultaneously reduce weight, enhance mechanical performance, and improve durability in demanding marine and offshore applications. The work also demonstrates how lightweight composites and optimized structural systems can absorb impact energy effectively and remain resilient under extreme offshore dynamic loading. By combining sustainable cementitious composites, structural optimization strategies, and robust modeling techniques, the work provides an integrated framework for developing next-generation resilient marine infrastructure. Section 8.1 states down the major conclusions drawn from each chapter, while Sect. 8.2 outlines directions for future research.