This workshop service repair manual covers the Mercury Mariner Marathon 25 outboard motor. Engineered for reliable performance, this water-cooled, CDI ignition outboard motor delivers 25 horsepower and utilizes a carburetor for fuel delivery. Its transmission features a lower unit with forward, neutral, and reverse gears, designed for efficient operation. This manual is intended to provide comprehensive information for maintaining and repairing this robust marine engine. The scope of this English-language manual is extensive, detailing all aspects of the Mercury Mariner Marathon 25. It includes in-depth maintenance procedures, such as recommended fluid types like marine gear lubricant and unleaded gasoline with an 87 minimum octane rating, troubleshooting guides, and essential technical specifications. Safety guidelines are also integrated throughout. This resource is invaluable for mechanical technicians and owners seeking to ensure the longevity and optimal functionality of their outboard motor.