The Staten Island Ferry is a fare-free passenger ferry route operated by the New York City Department of Transportation. The ferry's single route runs 5.2 miles (8.4 km) through New York Harbor between the New York City boroughs of Manhattan and Staten Island, with ferry boats completing the trip in about 25 minutes. The ferry operates 24 hours a day and 7 days a week, with boats leaving every 15 to 20 minutes during peak hours and every 30 minutes at other times. Apart from NYC Ferry's St. George route, it is the only direct mass-transit connection between the two boroughs. Historically, the Staten Island Ferry has charged a relatively low fare compared to other modes of transit in the area; and since 1997, the route has been fare-free. The Staten Island Ferry is one of several ferry systems in the New York City area and is operated separately from systems like NYC Ferry and NY Waterway.

The Staten Island Ferry route terminates at Whitehall Terminal, on Whitehall Street in Lower Manhattan, and at St. George Terminal, in St. George, Staten Island. At Whitehall, connections are available to the New York City Subway and several local New York City Bus routes. At St. George, there are transfers to the Staten Island Railway and to the St. George Bus Terminal's many bus routes. Using MetroCard fare cards, passengers from Manhattan can exit a subway or bus on Whitehall Street, take the ferry for free, and have a free second transfer to a train or bus at St. George. Conversely, passengers from Staten Island can freely transfer to a subway or bus in Manhattan after riding the ferry.

The Staten Island Ferry originated in 1817 when the Richmond Turnpike Company started a steamboat service from Manhattan to Staten Island. Cornelius Vanderbilt bought the Richmond Turnpike Company in 1838, and it was merged with two competitors in 1853. The combined company was in turn sold to the Staten Island Railroad Company in 1864. The Staten Island Ferry was then sold to the Baltimore and Ohio Railroad in 1884, and the government of New York City assumed control of the ferry in 1905.

In the early 20th century, the city and private companies also operated ferry routes from Staten Island to Brooklyn. Owing to the growth of vehicular travel, all of the routes from Staten Island to Brooklyn were decommissioned by the mid-1960s; but popular demand preserved the route to Manhattan. By 1967, the Staten Island-to-Manhattan ferry was the only commuter ferry within the entire city. A fast ferry route from Staten Island to Midtown Manhattan ran briefly from 1997 to 1998; proposals to revive the route resurfaced in the 2010s.

With 16,687,800 riders in 2024, the Staten Island Ferry is the busiest ferry route in the United States and the world's busiest passenger-only ferry system, thanks largely to the lack of other transit connections between Staten Island and the other boroughs. The ferry is also popular among tourists and visitors due to the free-of-charge views of the New York Harbor a trip provides. The ferry has been featured in several films.

Before the New York City area was colonized by Europeans, the indigenous Lenape Native Americans used boats to traverse waterways—including present-day Arthur Kill, Kill Van Kull, and Raritan Bay—of the area then known as Lenapehoking, which included present-day Staten Island, Manhattan, and New Jersey. The area would first be colonized as part of Dutch New Netherland in 1624. New Netherland became the British Province of New York in 1664, and the British province finally became part of the United States in 1776. During the 18th century, the City of New York occupied only the southern tip of Manhattan, and Staten Island was not incorporated within the greater city. At the time, ferry service along New York Harbor between Staten Island and Manhattan was conducted by private individuals in "periaugers". These shallow-draft, two-masted sailboats, used for local traffic in New York Harbor, were also used for other transport in the area.

Cornelius Vanderbilt, an entrepreneur from Stapleton, Staten Island, who would become one of the world's richest people, started a ferry service from Staten Island to Manhattan in 1810. Just 16 years old, he had sailed extensively enough in his father's periauger that he could easily navigate the New York Harbor Estuary on his own. He was given $100 for his birthday in May 1810, which he used to purchase a periauger called Swiftsure. Vanderbilt used his boat to transport passengers from Staten Island to the Battery at Manhattan's tip. He competed against other boatmen providing service in the harbor, who called him "Commodore" because of his youthful eagerness; although the nickname was intended to be jocular, it applied to him for the rest of his life. The War of 1812 meant restricted access to New York Harbor from elsewhere along the East Coast. During the war, Vanderbilt profited from carrying cargo along the Hudson River, and he bought extra boats with these profits. After the war, he transported cargo in the harbor, earning even more money and buying more boats.

Around the same time, US Vice President Daniel D. Tompkins secured a charter for the Richmond Turnpike Company as part of his efforts to develop the village of Tompkinsville, which would become Staten Island's first European settlement. The company was incorporated in 1815, and the land comprising Tompkinsville was purchased around this time. The company built a highway across Staten Island; it also received the right to run a ferry to New York. The Richmond Turnpike Company began to operate the first motorized ferry between New York and Staten Island in 1817, Nautilus, which was commanded by Captain John DeForest, the brother-in-law of Cornelius Vanderbilt. This new ferry broke the short monopoly on steamboat operations that had been held by the Fulton Ferry, which had connected Manhattan and Brooklyn since it began operation in 1814. Since the steamboats provided much faster means of transportation across the harbor, Vanderbilt sold all his ships to his father in 1818. He subsequently started working for Thomas Gibbons, a small-steamboat operator, operating steamboat lines for Gibbons in New Jersey before later operating his own lines in New York.