Hachijōjima (八丈島) is an island in Tokyo prefecture, some 300 kilometers south of Tokyo with 8,000 residents. Its dialect is on the list of UNESCO endangered languages.
Tokaikisen  operates a daily overnight ferry from Tokyo's Takeshiba pier, near the Daimon metro station. Leaving Tokyo at 22.30, and arriving at 9.30. Boards at 22:10. (Current as of 22May19) prices vary seasonally but expect to pay around ¥10750 for a reclining seat. ¥22,830 for a first class cabin.
From Haneda (HND), Take Monorail to Hamamatsucho station (Adjacent to the JR Yamanote Station) Exit at street level, turn Right, walk ~ 8~10 minutes to ferry Terminal. There will be a Large ship's Mast in a larger open area. Ticket windows are inside terminal and open at 20:00 however the Tourist Information office - located just to the left of the Ticket windows - seems to be open all day and they can sell you tickets. They speak English and take Credit cards. There is a coffee shop / gift shop inside the terminal, the ubiquitous vending machines, and coin storage lockers. So if you get there early, you can stash your gear and go do something else till boarding time!
From Takeshiba to Hachijojima is mostly at night, however coming from Hachijojima to Tokyo is during the day. Either way, its a nice way to go! (I'd recommend Ship one way, Fly the other)
Note: These ships/ferry's are NOT those disgusting, hyper-stabilized, super-mega floating hotels (a.k.a Cruise ships), but rather ships with character, history and charm. They are clean, safe and comfortable and are a really pleasant and relaxing way to travel. The only thing to be aware of if your easily affected by sea-sickness, be prepared.
ANA (All Nippon Airways) flies between Haneda (HND) airport in Tokyo and Hachijōjima (HAC) three times a day. Prices vary seasonally, but expect to pay around ¥25-30,000 return. You can get around this by booking on the english version of the Japanese site. From this you will have access to the lowest fares. If you book using Orbitz or other, ANA cannot easily modify your ticket if needed.
WARNING: (Pay attention here or you will NOT be a happy camper!): If you are planning to fly from HAC to HND and will connect to an international flight, plan on AT LEAST 60 minutes just to deplane at the Domestic terminal and arrive at the departures level of Haneda'a International terminal. HND is that big! It took me 44 minutes on a quiet morning. On a busy day, you'll need the time. Also you then have to clear security and Passport control which is sometimes 10 minutes, and sometimes hours... The point is, plan on at least two hours+ to connect to an international flight.
There are rental Cars available on the island for around ¥3000 / day. Scooters & Motorcycles are also available. However do be aware you WILL need an international drivers license in order to rent a car. (You can get them from AAA)
Most accommodations have bikes for hire. Including Electric Bikes
The Public bus service runs on the main route about every two hours, which will get you to the Ferry terminal, the city, and several of the Onsens. In some areas service is as few as 2-3 times daily. The bus schedules are in Japanese, but its pretty easy to find someone who can write the english names of the stops you need. There is a Two-Day Pass "BU.S.PA" for ¥1000 that is good for the bus and most of the Onsens
There are taxis on the island as well. Fuji hire phone=04996-2-0416 has drivers who speak good English.
I would recommend rent a car for a day or two, then use the bus. A wee bit of planning around the bus schedule and it works well.
There are Tourist information offices at the Ferry Terminal, Airport, and downtown. They speak passable english and are VERY helpful. I would highly recommend that this be your first stop. They can literally help with everything.
Hunt for for glow in the dark mushrooms, diving, snorkeling, and trekking to secret waterfalls in the mountains.
The island is covered by major mobile networks, including docomo, au and softbank. Some areas have weak connection. TV channels are the same ones as in Tokyo. Free public wifi is very limited, but found at the Tourist Information Office  in Okago.