Nova Star says the number of passengers riding the ferry from Yarmouth to Portland doubled last month to just over 13,000 passengers, about 421 passengers on average per day.
It says about 6,800 passengers boarded the vessel in June.
The company says its goal is to have between 500 and 700 passengers per day on average during its peak season.
Nova Star president Mark Amundsen attributes the growth to word-of-mouth promotion from passengers who have recommended the voyage to others.
The Nova Scotia government recently announced that the entire $21 million it had committed over seven years for the ferry has been spent by the operator only two months into its first season.