Digital Twin Technologies in Sustainable Maritime Systems: A Systematic Review and DT Maturity Framework

Digital Twin (DT) technologies are increasingly transforming maritime and port systems by enabling real-time monitoring, predictive analytics, operational optimisation, and sustainability-oriented decision-making. Despite growing academic and industrial interest, the integration of DTs into sustainable maritime ecosystems remains fragmented, particularly in assessing digital maturity and sustainability performance. This study follows the PRISMA 2020 methodology to systematically review 26 peer-reviewed studies from Scopus and Web of Science. Through thematic synthesis, based on inductive coding and the identification of recurring patterns across the reviewed studies, four Digital Twin dimensions and a four-level maturity framework supported by Key Performance Indicators (KPIs) were derived: smart port development, artificial intelligence integration, energy optimisation, and environmental governance. Based on the findings, the study proposes a DT Maturity Framework for sustainable maritime systems, structured across progressive levels of technological integration, operational intelligence, sustainability alignment, and governance capacity. The framework provides an operational, multidimensional approach to assessing DT maturity across heterogeneous maritime ecosystems. The study contributes to the emerging literature on sustainable maritime digitalisation by offering a systematic conceptual synthesis that can support future research, strategic planning, and policy development in smart and sustainable port ecosystems. The proposed framework constitutes a conceptual assessment model whose empirical validation is identified as a priority for future research. As a literature-derived conceptual assessment model, the proposed framework requires empirical validation before its maturity levels and associated KPIs can be considered empirically established.