This thesis investigates the alternative fuels uptake in the global fleet, aiming to identify the key factors influencing adoption patterns and to project emerging trends. The study analyzes the current composition of the fleet, vessel characteristics (type, age, size), operator behavior, national fleet differences, and the influence of regulatory frameworks on fuel choice. Findings indicate that Liquified Natural Gas (LNG) dominates as the preferred alternative fuel, particularly among larger vessels and categories such as LNG carriers, Ro-Ros, containers, and passenger/cruise ships. Methanol adoption is steadily increasing, especially among container vessels and industry-leading operators, while ammonia and hydrogen are emerging options in the newbuild orderbook. Biofuels remain primarily limited to older vessels due to their drop-in capability. Newer ships exhibit higher alternative fuel adoption and a more diverse fuel mix, while larger operators demonstrate greater adoption intensity, reflecting their financial capacity and strategic resources. Regional analysis shows that EU-flagged ships lead adoption due to regulatory incentives, the Japanese fleet aligns closely with global trends, and the Chinese fleet lags overall. The study highlights that alternative fuel adoption is context-specific: vessel operational profiles, market trade routes, operator financial capacity, and long-term strategic vision all shape fuel choice. Short-term feasibility and long-term decarbonization goals must be balanced to optimize adoption strategies. These findings provide a comprehensive understanding of the current state of maritime decarbonization and offer a methodological foundation for ongoing analysis of the evolving global fleet.