The Mersey ferry has retained its certification for meeting international environmental standards.
Since 2006, ferry operator MerseyTravel has been working towards cutting emissions in several ways.
These include running ferries at a slower speed, installing new energy control systems setting up giant ventilation fans to improve efficiency.
All these initiatives have helped the company reduce its carbon emissions by seven per cent over the last three years.
Now, MerseyTravel has been told it has retained its Environmental Management Systems certification.
Chair of the organisation Mark Dowd said: "We were the first passenger authority in the country to gain this certification six years ago and the environment remains very important for our future transport plans too."
Neil Scales, chief executive and director general, added that the firm's environmental strategy "continues to be an important element of all we do".
"To be reaccredited in 2009, Year of the Environment, makes the achievement that extra bit special," he concluded.