Mayor Bill de Blasio on Monday staunchly defended his administration’s plans for shelling out another $43 million in ferry purchases for its money-losing fleet, saying “this is an investment in the future.”

“This is not just about today – it is about tomorrow,” Hizzoner also told NY1, responding to a Post report that he plans to spend the additional funds on five new boats.

“New York City needs more transit options for the future, … [and] ferries work.”

The overly optimistic mayor also said he’s hopeful the city ferry system will soon connect with MTA subways and buses, so riders using both services receive free transfers and aren’t socked twice on fares.

“When that day comes, you will see more people take the ferry,” said de Blasio.

However, he offered no evidence that the city or MTA would subsidize the lost fares.

The latest ferry fleet push comes just months after City Hall forged full speed ahead with another $84.5 million purchase over the worries of City Comptroller Scott Stringer. It swells the total amount sunk into the program to $637 million.

Just 18,000 people rode the ferries on an average weekday during the spring, with those trips subsidized at a rate of $10.73 per ticket