The maritime industry is under increasing pressure to decarbonize in response to global climate targets and stricter environmental regulations. Alternative marine fuels such as hydrogen, ammonia, and liquefied natural gas (LNG) have emerged as potential solutions to reduce greenhouse gas emissions from shipping. This study presents a comparative analysis of these three fuels based on key parameters including energy density, storage and handling requirements, safety considerations, infrastructure readiness, economic feasibility, and lifecycle emissions. While hydrogen and ammonia are widely regarded as zero-carbon fuels at the point of use, challenges related to production methods, storage complexity, and safety risks persist. LNG, although not entirely carbon-free, offers a transitional pathway with lower emissions compared to conventional marine fuels. The paper evaluates the advantages and limitations of each fuel and assesses their suitability across different vessel types and operational profiles. The findings aim to support stakeholders in selecting sustainable fuel alternatives and contribute to the broader transition toward decarbonized maritime transport.