New York City Mayor Bill de Blasio wants to increase capacity for the NYC Ferry service after a year of higher than expected use. Since its launch in May 2017, the four operating ferry routes carried 3.7 million passengers, according to city data. De Blasio said he's surprised by the popularity of the service, which is expected to have 9 million passengers by 2023 — double the initial estimates.

"We had no projection for anything like this but the response to NYC Ferry has been overwhelming," said de Blasio at a press conference announcing the expansion in Bay Ridge, Brooklyn. 

De Blasio is trumpeting the service's expansion as a success, but other elected officials are pushing back against his proposal to spend $300 million on NYC Ferry over the next five years. The mayor also wants to double the number of boats and add ferry stops on the Lower East Side and Soundview in the Bronx.

City Council Speaker Corey Johson says the money would be better spent on providing half-priced MetroCards for low-income New Yorkers, a centerpiece of the council's budget proposal.

"The vast majority of New Yorkers rely on our public transit system and it's unrealistic to think ferries can lift people out of poverty," said Johnson.

De Blasio has yet to fully endorse the "Fair Fares" proposal. He says that it should be the responsibility of the state-run MTA rather than city taxpayers.

The mayor and city council must agree on a $90 billion budget before the city's fiscal year begins on July 1, 2018.