This document pertains to the Mercury Mariner 25 Marathon Outboard, a gasoline-powered outboard motor designed for marine propulsion. Engineered for reliability and performance, this outboard motor features a water-cooled system and delivers 25 horsepower, making it suitable for a range of boating applications. Its robust construction and efficient design underscore Mercury's commitment to quality marine engineering. This Workshop Service Manual provides comprehensive guidance for the repair and overhaul of the Mercury Mariner 25 Marathon Outboard. It covers essential maintenance procedures, technical specifications, and troubleshooting steps, all presented in English. The manual is intended for owners, mechanics, and technicians, equipping them with the necessary knowledge to maintain the optimal performance and longevity of the outboard motor, adhering to general automobile practices for service.