The maritime industry is undergoing a transformative shift towards reducing environmental impact and meeting stringent emission regulations. Alternative fuels such as LNG, biofuels, hydrogen, ammonia, and methanol are at the forefront of this evolution. Liquefied Natural Gas (LNG) stands out for its lower emissions and higher energy density, but challenges in cryogenic storage and infrastructure hinder widespread adoption. Biofuels offer carbon-neutral solutions with combustion compatibility, yet face constraints in feedstock availability and energy density. Hydrogen emerges as a zero-emission fuel with superior energy efficiency, despite challenges in storage, production, and infrastructure similar to LNG. Ammonia, known for zero carbon emissions and ease of storage, presents safety concerns and requires engine modifications. Methanol, with ease of storage and lower emissions, struggles with energy density limitations. The maritime sector's future propulsion relies on navigating these alternative fuels' benefits and addressing their respective challenges for sustainable and efficient operations.