In this, the fourth meeting in the Ocean Worlds series, we focus on the ice-water interactions occurring within ocean worlds beyond Earth, from a multi-disciplinary and inter-disciplinary perspective. Considering them in detail should lead to new hypotheses testable by future spacecraft missions. As with past Ocean Worlds meetings, a primary motivation is to engender a cross-fertilization of ideas and expertise by soliciting contributions from both the Ocean Sciences and Planetary Sciences communities. Consequently, contributions are invited that address any aspects of this broad ice-water interaction theme, across the Planetary and Ocean Science fields, including geophysics, hydrogeology, geochemistry, and microbiology.