This workshop repair manual covers the Mercury Mariner 25 HP Marathon outboard engine. Engineered for reliability and performance, this water-cooled outboard offers 25 horsepower and is designed for a variety of marine applications. Its robust construction and efficient design ensure dependable operation, making it a suitable choice for recreational and professional use. This comprehensive English-language manual provides essential information for the maintenance, service, and troubleshooting of your Mercury Mariner 25 HP Marathon outboard. It details scheduled maintenance, fluid specifications, parts replacement, and diagnostic procedures for common issues. This resource is intended to assist owners, technicians, and mechanics in keeping the engine in optimal working condition.