This manual covers the Mercury Marathon Seapro, a 2-stroke jet drive engine designed for reliable performance. Offering 20 HP and 25 HP options, this engine is engineered for demanding marine applications. Its robust construction and efficient jet propulsion system ensure dependable operation in various water conditions. This service manual provides comprehensive guidance for the maintenance and repair of your Mercury Marathon Seapro. It details essential procedures, including lubrication, service schedules, and cooling system maintenance, alongside technical specifications and troubleshooting information. With clear, step-by-step instructions and illustrations, this manual is an indispensable resource for owners and technicians seeking to preserve the longevity and performance of their engine.