North Fork

The North Fork of Long Island, New York, contains the two towns of Riverhead in the west and Southold in the east.
It is the most rural part of Long Island, but has two villages of note: the village of Riverhead, county seat of Suffolk county (though most county offices are further west) and home of Splish Splash water park, the Long Island Aquarium, and a host of other sites; and Greenport, a small village almost at the end of the Fork, home to a substantial maritime and railroad history. In between the two lie Aqueboque, Jamesport, Laurel, Mattituck, Cutchogue, Peconic, and Southold. East of Greenport are East Marion and Orient Point, the easternmost village on the fork. None of these are large or host particularly many attractions.

The South Fork or the Hamptons and Montauk point are just south of the North Fork. It is an easy drive of easier to take a small ferry to Shelter Island, drive through to the next ferry to Sag Harbor and explore there as well.
Heading west from the North Fork, you can visit Long Island and head further west to New York City.
Long Island has many enjoyable places to visit, including nice villages. Beautiful ocean beaches, restaurants, and tours are available of Gold Coast Mansions, that dotted the coast during the era of the Great Gatsby. For groups of 50 or more tour guides are available. If small groups, you can visit the mansions online and check for events and availability.
Staying in the North Fork or returning if a long trip there are many things to do. Mostly it is a quiet place and relaxation and tranquility along with a picturesque setting are part of what makes the North Fork an enjoyable destination.

The North Fork of Long Island is only 80 miles from Manhattan. This area offers a low key lifestyle for both families as well as couples that want to get away from the hustle and bustle of the city. It is also cheaper than the South Fork of Long Island which is appealing to many people.

By car

The Long Island Expressway (more commonly known as the L.I.E, officially I-495), which comes from Midtown Manhattan, ends in Riverhead, where Long Island forks. From Riverhead, NY-25 serves as the both the main route out to the North Fork and the main street for several hamlets and villages. Suffolk Co. Route 48 provides a more northerly alternative until Greenport.
NY-25 also continues further West into Queens, offering a less hectic alternative to the L.I.E.

By bus

The Hampton Jitney provides access to various points the North Fork from Manhattan several times daily. As train service to the North Fork has been cut, the Jitney has increasingly gained popularity. It runs considerably more frequently than the train, although the schedule is subject to seasonal variation.
A one-way ticket from New York to the North Fork costs $19.00 bought in advance, and $21.00 bought on board.

By train

Although it was the original terminus for the Long Island Rail Road (LIRR), the North Fork's Greenport Branch now sees the least service of any LIRR branch. Schedules are available at the LIRR website On weekdays there are only 4 daily trains to Greenport from Penn Station in Manhattan, all of which require a transfer to a diesel scoot at Ronkonkoma. On Fridays between Memorial Day and Labor Day, 5 trains go from Penn Station to Greenport.
On weekends the service is similar with 4 trains departing at different times, all of them terminating in Greenport.
A one-way off-peak ticket from Manhattan or Brooklyn to anywhere on the North Fork costs $19.75 if bought in advance; tickets cost more on-board or during peak times. Train stations on the North Fork lack ticket machines and therefore no penalty will be assessed for buying tickets on board when going towards Manhattan.

By ferry

Frequent car ferries run to the North Fork from Connecticut and Shelter Island. From Shelter Island, the North Ferry runs every 10-20 minutes between Shelter Island Heights and Greenport, calling next to the train station. Fares are reasonable at $10.00 one-way and $15.00 return for a vehicle and driver and $2.00 for foot or car passengers. Bicycles and motorcycles cost extra, but less than a car.
From Connecticut, the Cross Sound Ferry runs hourly trips between 7am and 8pm between New London and Orient Point, at the easternmost end of the Fork, on five different boats, including a passenger-only fast ferry and a repurposed World War II landing craft. Fares are considerably higher than the Shelter Island, with one-way trips starting at $14.50 for foot or car passengers on the car ferry and $51.00 for a vehicle and no round-trips available. Tickets on the fast ferry for foot passengers cost even more. Due to fuel costs, the ferry company also charges a 4.9% fee the call the "floating surcharge"-one hopes the boat doesn't sink if someone forgets to pay it!
West of the North Fork, the Bridgeport and Port Jefferson Ferry provides several daily trips from Bridgeport to Port Jefferson. Port Jeff is located on NY-25A, which one can follow to NY-25 in Riverhead. Fares are similar to the Cross Sound Ferry. See the Port Jefferson article for details.

As this is Long Island, and the least populous part of it at that, the best way to get around by far is with a personal vehicle. However, bus and train service are (barely) provided, and Greenport and Riverhead are compact and quite walkable.

By car

The main roads on the North Fork are NY-25 and Suffolk-48, which merge in Greenport before continuing on to Orient Point as NY-25. For most visitors, NY-25 will be the road of choice, as it is closer to the towns of interest that hem Peconic Bay.
Taxis are available from Island Cab, but expensive as they are on all of Long Island

By foot

Riverhead and Greenport are compact and walkable – indeed, this is the best way to experience them. Everywhere else on the North Fork, however, is not.

By bus

Suffolk Transit's S92 serves the entire North Fork (as well as Easthampton and Sag Harbor on the South Fork). The bus runs roughly every hour or half hour (depending on the time of day) from Orient but only until 3:35PM! There is additional morning service and one additional evening bus from Greenport only. On the other hand, unlike almost every other Suffolk Transit bus, the S92 has Sunday service in the summers, but the base fare is higher than usual at $2.25. As is usually the case with Suffolk Transit, don't expect reality to hew closely to the schedules.

By train

The aforementioned trains from Riverhead (and ultimately Ronkonkoma) to Greenport can also be used to travel between towns on the North Fork; in this case the fare is $3.00 bought on board the train. The train makes intermediate stops at Mattituck and Southold. As there are only 4 or 5 trains a day and neither intermediate stop is pedestrian friendly, the train is of limited utility (though it is generally more reliable than Suffolk Transit).

The North Fork of Long Island has many bed and breakfasts as well as inns and hotels. All of the bed and breakfasts and inns and hotels are located either along the beach or next to vineyards.

The logical next point is to take the ferry to Shelter Island, site of the 1947 Shelter Island Conference. From there, you can take the ferry to Sag Harbor and go to either Montauk or The Hamptons, as part of an East End circle tour of sorts.
Alternatively, you can take the ferry to New London and continue there. From the New London ferry terminal it is a quick and easy drive east to Rhode Island and Boston or north to Vermont and new Hampshire. For a really off-the-beaten-path option, take the ferry to New London from there take a ferry to Fishers Island, an island off the North Fork accessible only from New London.