A power train for an amphibian operable in land and marine modes includes a prime mover, at least a first land propulsion unit, a first marine propulsion unit, a second marine propulsion unit, and at least one speed change transmission. The prime mover is arranged to drive the at least first land propulsion unit through/via the at least one speed change transmission in land mode, and the prime mover is arranged to drive the first marine propulsion unit and the second marine propulsion unit through/via the at least one, or another, or combinations of, speed change transmission in marine mode. In addition, the present invention provides an amphibian comprising the power train.