New York City Mayor Bill de Blasio wants an array of new ferry routes linking Manhattan to other city boroughs, to serve growing populations in redeveloping neighborhoods, and ease notoriously long and painful commutes for workers.

In his state of the city address in late January, de Blasio proposed developing a dozen new ferry routes by the end of this decade – across the East River to Brooklyn, Astoria and the Bronx, skipping along Manhattan’s East Side neighborhoods, and even to distant Coney Island and Rockaway.

Officials in Staten Island, the ferry system’s busy port, want de Blasio to go even farther, with ferries to the lower harbor to serve remote South Shore neighborhoods.

De Blasio’s commitment gratified advocates who for years argued the city virtually ignored its waterfront assets.

“We’re sort of experiencing a renaissance,” said Roland Lewis, executive director of the Metropolitan Waterfront Alliance, a union of community and industry groups that seeks smarter use of the city’s waterways. “The city’s population is growing, and much of the population that’s growing is along the waterfront.”

Private ferry companies began operating between New York and New Jersey in the late 1980s and grew along with the city’s financial services industry. The waterways’ value were obvious after New York emergencies, when boats came to the rescue – like the evacuation of lower Manhattan after the Sept. 11, 2001 terror attack, and during blackouts and Hurricane Sandy when the subways were out of commission, Lewis said.

The city began new ferry service on the East River with an addition to the venerable Staten Island ferry in 2011 and it exceeded expectations, Lewis said.

“They anticipated about 500,000 riders a year, with a (public) subsidy of around $4 a head,” Lewis said. Instead the boats got 1 million passengers in the first year and the city’s subsidy was half at $2 per trip, he said.

“That’s one-seventh of the subsidy for an express city bus,” Lewis said. “We all went to school on the East River ferry. We said, let’s see if this works in Astoria, the Bronx.”

Easing the commuting pain for working families is a big part of this idea. With bus and subway connections, some borough residents spend two hours getting to work – as long as middle-class commuters from the suburbs.

“You could do that in a third of the time with a ferry,” Lewis said.