Ferries are ships of various size, which carry passengers, and in some cases vehicles, between ports on a schedule. They are typically motor ships, though some heritage routes can be run by steam ships, or even sailing vessels, and some remote ones can use human propulsion.

While some ferries are open-deck vessels which cross a narrow strait for daily commuting, others have cabins and other amenities, similar to cruise ships or ocean liners, and might be tourist attractions in their own right. On rivers and lakes and in coastal archipelagos there may be ferries that are part of the local public transportation network, sometimes called water buses.

Reliability is a consideration: ferries may be cancelled or delayed due to bad weather, sometimes for weeks on end in winter, or may just be inexplicably late like every other form of transport. Don't plan a tight connection between a ferry and something crucial like a long haul flight. Sometimes the schedules leave little choice: the onward bus or train is due to depart 30 minutes after the ferry docks and may not wait for a late sailing. In general the faster the ferry, the more prone it is to disruption, as it will be a skittery hydrofoil, not a staid conventional craft. (Some routes have both, with the hydrofoil taking only foot-passengers in summer while the conventional ship carries vehicles year round.) In bad weather the ferry and the flight will be cancelled about the same time – flights to a small island are probably in rinky-dinky little aircraft. But later the aircraft will have more flexibility to dash over during a lull, whereas once the ocean gets mad it stays mad. You'll need to keep in touch with your carrier, who will know what's going on when (including alternate transport) and who gets priority. The midwife and the TV repair van always get priority.

Trains used to be commonly laden on ferries in the olden days, but train ferries are increasingly a dying breed because tunnels on the one hand and ever cheaper airfare on the other are undermining their business case. The 45-min train ferry passage between Germany and Denmark (Puttgarden–Rødby) – formerly the main railway connection to Scandinavia – was discontinued in 2019. For freight trains this method is still somewhat common with "trajects", as they are called, going from Sassnitz (Rügen) as far away as Klaipeda to transport freight trains complete with their content.

Some minor cable ferries still use human power for propulsion, such as on hiking trails. There may be rowing boats instead (usually three of them), in which case it is important to never leave one side of the crossing without access to them.

Check insurance and rental conditions. Ferries may not legally be regarded as roads, so your insurance may not cover incidents on board. Some rental contracts forbids taking the car onto a ferry. Whether this is an issue largely depends on region and type of ferry, but ask and read the fine print.

If you travel by road or rail, it's obvious from the map where your route lies, and it's unlikely to change much from year to year. Travel across water and it's not always obvious which routes are running or practical, for instance whether you can take a car. Some European routes lead across a plausible ferry route not serviced by any ferries.

The pages below outline some of the main networks. Look on specific country and city pages for more detail, and always check the ferry operators' timetables for prices, times, bookings, and live updates on disruptions.

• Alaska Marine Highway is a chain of ferry routes from Bellingham in Washington State through Juneau, Alaska and out to the Aleutian Islands. No single ferry sails the entire route.
• Baja ferries cross the Sea of Cortez (Gulf of California) between mainland Mexico ports at Mazatlan and Topolobampo and La Paz in southern Baja California
• Baltic Sea ferries crisscross between all the major ports around that sea, especially between Sweden, Finland and the other EU countries to save a long drive.
• Ferries in the Caspian Sea are simply freighters that take passengers. They ply erratically from Baku in Azerbaijan to Turkmenbashi in Turkmenistan, and to Aktau in Kazakhstan, and sometimes between other ports. All your ingenuity and patience will be sorely tested on these routes.
• Cook Strait ferries sail between Wellington on North Island and Picton on South Island in New Zealand. Freight train wagons are loaded onto the ferries for transfer between the North and South islands.
• Ferries in the Mediterranean are an extensive network ranging from the Spain-to-Morocco shuttles, the Italian islands such as chic Capri and fiery Stromboli, Greek islands like Crete and Naxos redolent of antiquity, and the bosky Adriatic archipelago off the coast of Croatia. The few Black Sea ferries are also described here.
• Ferries in the Red Sea regularly cross its narrow northern arms between Hurghada, Sinai and Aqaba. Ferries also carry pilgrims across the broader sea to the south between Egypt, Sudan and Saudi Arabia, but these are not sailing in 2020.
• Ferry routes to Great Britain are principally across the Channel from France, with ferries also from Spain, the Channel Islands, Belgium and Netherlands; and across the Irish Sea to Ireland (north and south) and the Isle of Man. Within the UK, there are ferry routes from the "mainland" island of Great Britain west to the Scottish Hebrides and north to the archipelagos of the Orkneys and the Shetland Islands. Ferries no longer sail to Great Britain from Germany, Denmark, Norway, the Faeroes or Iceland.
• Hurtigruten is a ferry plying the coast of Norway from Bergen all the way round the north cape to Kirkenes.
• Lake Tanganyika in the Great Rift Valley of East Africa is served by MV Liemba along its 676 km length.
• Australia has many cable ferries for cars at rural river crossings. Ferries also operate between mainland Australia and several offshore islands, most notably to Kangaroo Island, K'gari and Tasmania.
• Hainan is connected to Leizhou on the Chinese mainland by ferry. Road vehicles and train carriages are loaded onto the ferries for the crossing.

Great views from ferries:

• Manhattan and the Statue of Liberty from the Staten Island Ferry.
• The cliffs of Dover from the channel ferries.
• Castles and vineyards from the Middle Rhine Valley car and foot ferries.
• The skyline of the Old City of Istanbul from the ferries crossing the Bosporus.
• Stockholm Archipelago and Finnish Archipelago Sea from the Baltic Sea ferries, or the local ones.
• Liverpool Pier Head and waterfront from the Mersey Ferry, England.
• Star Ferry in Hong Kong
• All of Sydney Harbour on any Sydney ferry lines from F1, F4, F5 F7, F8, F9, the eastern part of F3 and the southern part of F6.
• Penang Ferry between George Town and Butterworth.
• The state of Texas operates ferries across the mouth of Galveston Bay, between Galveston Island and the Bolivar Peninsula

Some cities have ferry services that operate almost as a bus service along a major river, or across a lake or harbour, making them very much an integral part of the city's public transportation network. They may be the most memorable travel you'll ever do. Great examples include:

• Bangkok has perhaps the world's best known water bus service called the Chao Phraya Express Boat, which operates down the Chao Phraya River during daylight hours. In addition to the boats for local commuters, there are some more expensive boats geared for tourists that stop only at Bangkok's main tourist attractions along the river, but consider taking one of the local boats so you can observe the locals going about their daily commutes. There is also another water bus service called the Khlong Saen Saep boat service, which runs on a canal known as the Khlong Saen Saep, but it is primarily geared for locals.
• Cajun country with rope-hauled rafts, where alligators watch you from the bayou banks. Mind your step getting off!
• Ho Chi Minh City has the Saigon Waterbus, which travels down the Saigon River. Geared primarily for local commuters, it does not go to the major tourist attractions, with the exception of the first stop in the heart of the city opposite the Hotel Majestic. Nevertheless, hopping on the water bus is a good way to observe local life.
• Hong Kong harbour with the Star Ferries bouncing across, as well as numerous other ferries connecting Central with Hong Kong's outlying islands. There are also ferries operating less popular routes, often from rural piers to remote outlying islands. Known as kai to, these typically have much lower frequencies, sometimes only operating on weekends and public holidays, and are often nothing more than a motorised sampan.
• Penang has ferries crossing the Penang Strait between George Town on Penang Island and Butterworth on the mainland.
• Istanbul crossing the Bosphorus.
• London has a river bus service running on the River Thames running from Putney in the west to Barking in the east. It stops near some important tourist sites such as Greenwich, Canary Wharf and the Tower of London.
• Luxor crossing the Nile.
• San Francisco has several ferry networks linking it with Marin County across the Golden Gate Strait and several other cities across the San Francisco Bay.
• Venice has an extensive network of water buses, called vaporetto, between islands and with routes along the Grand Canal beneath the Rialto.
• The water bus down 1770 crossing the water around it.
• Lisbon has a network of ferries connecting the downtown area with suburbs across the Tagus River.
• Sydney has a network of ferries connecting the CBD with suburbs across the harbour. Perhaps the most useful one for tourists is the ferry to the suburb of Manly, where the famed Manly Beach is located.
• New York City has a network of ferries linking Manhattan with New Jersey and the outer boroughs.
• Stockholm has Waxholmsbolaget waterbus system serving its archipelago.
• Cancun has high-speed ferries to Isla Mujeres. High-speed ferries also operate between Playa del Carmen and Cozumel

Tickets: it's as variable as on other modes of transport. Peak season (summer weekends especially around an "island festival" or similar big event) you need to book early especially with a vehicle or for hydrofoils, or if you need an overnight cabin: do so at the same time you book your destination accommodation. Spaces are for a standard length car, with extra for caravans and trailers: check the maximum dimensions and any restrictions, e.g. on campergas tanks. Conventional ships often have last-minute capacity for foot passengers. Mostly you book online just the same as for flights, though some operators are still in a bygone century and respond by snail-mail. There's usually an office near the pier for late ticketing, or where you exchange your online voucher for a boarding pass. And some small ferries just wave everyone on and collect fares aboard.

Check-in: read the instructions and follow them – starting with directions to the harbour, which may not be where Satnav is urging you to go. If they say to be there at least an hour before sailing, which is standard advice for a car, then make sure you're on time. Otherwise your place will be re-assigned to the hopefuls in the unbooked queue, which you will be sent to join the back of. Those on foot can saunter up 15 minutes before sailing; those with bicycles need extra time since the vehicle ramp will close before the pedestrian access.

You may need to show photo ID even on a domestic route, and if the ferry crossing is an international border then all the business of passport and customs checks has to be factored in. However, unlike airports, ferries seldom have a separate baggage check-in and security screen. You tote your own bags, either yourself or in the car, but waiting in the vehicle queue is a good time to sort out what you need on board and what can stay in the car, which may be inaccessible on a locked car deck. Snacks, baby stuff, doggy bowl, spare clothes for the cold breezy deck?

Facilities at the ferry port vary: it may be a proper passenger terminal (perhaps integrated into the bus or railway station) with refreshments, seating and toilets, or just a fractious cattle-pen, or little more than a bus shelter. Sometimes it's just a lonely spray-lashed jetty. In some places the ferry calls only on demand, and you might need to both make sure that you are seen and show that you want to board the ferry – even if you booked the passage and the timetable says the ferry always calls.

Get on: many ferries are ro-ro, the vehicles are driven on by ramp, while foot passengers either board the same way or by a walkway or gangway. Motorists must pay very close attention to the deckhands, who know to the inch where they want you. On trips serving several ports you need to park in a specific section of the ship and facing a specific direction: you might have to reverse aboard. Set the hand brake very firmly and then some extra (and consider leaving the car in gear) – vehicles may shift about on all but the calmest seas, and some car platforms are mechanically tilted. Deactivate the alarm if possible: the moment the ship leaves harbour, all the car alarms will have a contest with the seagulls for who can screech the most plaintively. On a small open ro-ro you may be allowed to stroll between car, deck and saloon as you please, but on a large ferry you have to leave the car deck, with no access until shortly before landing. Bicycles also need to be secured there; bring at least a strap.

Ro-ros are so ubiquitous that other modes of getting on are becoming rare – enjoy them soon before they disappear into a transport museum. There are still hovercraft ferries, places where cars are loaded by crane into the hold (along with a protesting consignment of sheep), and great tropical rivers where the "international frontier" means teetering along planks across a muddy embankment. Sometimes entire trains trundle aboard.

Once aboard: there may be open luggage racks as on trains, or coin-operated lockers, or a secure room. Seating is often assigned on hydrofoils but finders-keepers on conventional ships: you're trying to finesse the best views, the least draughts and smells, and the least objectionable neighbours. If you've booked a cabin, old school you collect the key from a purser in a peaked cap, but modern ships may adopt the style of a hotel reception lobby; or you may simply have a room access code on your ticket, to key in or get scanned by the lock.

Finish up any urgent mobile phone calls or internet look-ups quickly, as the ferry will soon move out of range of land-based networks. That's perhaps one reason why even fewer people listen to the ship safety announcement than they do to an airline safety demo, unless they're trying to learn the word for "lifejacket" in Finnish, Gaelic or Bahasa Indonesia.

Get off: promptly is the standard rule, but ferries that arrive in the early morning may let you rest aboard till breakfast, which means more revenue for them. Drivers still need to move their vehicle ashore promptly, to avoid locking in others, but may then walk back aboard for breakfast. On a scenic short-haul ferry, you might just want to sail there and back without disembarking. That's usually possible, but sometimes they shoo you off and you can't board the immediate return sailing. That's especially likely on city waterbuses, to deter down-and-outs from turning the ferry into a mobile flophouse.

Facilities aboard can differ a lot; while you will be lucky to find a toilet on a small ferry, a larger ferry can have a whole shopping mall aboard. International ferries might have duty-free shopping, or a casino.

Many ferries on longer passages have restaurants. In some cases booking a table when buying the ticket is cheaper and lets you go past the queue. Beside the food itself, they are a good pastime, but also an income for the shipowner – sometimes the budget options are no good value. Try to check the offerings and consider whether having packed food (and water!) is worthwhile.

Having your own pastime (books, playing cards, whatever) is worthwhile if the alternative is spending money in a bar or just sitting in a crowded lounge. On the other hand there may be nice seascapes, playing rooms and other diversions.

Some ferries on longer routes have cabins and other facilities that are close to those on a cruise ship. On some routes cabins will be provided for all passengers and may be included in the ticket price, but it is more usual to have to book a cabin as an add-on. There are often not enough cabins to meet the demand at busy times of year, and it may be necessary to book a cabin several months in advance. Cabins may be available also on day passages, often for a cheaper price.

Overnight ferries often also offer cheaper basic accommodation. This might be dormitory beds, or reclining seats.

You may also be able to travel overnight without booking accommodation. In this case there may be a rush when boarding starts to get the best sleeping places, such as bench seats in quieter parts of the ship.

Once a couple of kilometers off the coast mobile phone connections will often not work. Ferries with crossings longer than an hour sometimes provide Wi-Fi connections. These are often provided for a fee via purchasing a scratch card with a one-off access code, or by entering your card details on a sign-up page. If you book a business class ticket or a cabin these are usually included in the price. In some cases the ferry provides its own mobile phone network, with connections forwarded via satellite and roaming charges reflecting the costs of this solution. The Wi-Fi connection may also be slow and shaky, especially if you share a low-bandwidth outgoing link with everybody else.

Avoid the open deck in harsh weather and perhaps at night.

Check the emergency instructions and check how to get to the lifeboats or life rafts (possibly in darkness and smoke, and a severe list) and how to find life jackets (also the children's size ones, if relevant). Note alternative routes, especially on lower decks, as in case of fire or flooding the normal route may get closed. Ships of all kinds can sink quickly, but this is especially true for RoRo ships (those with lorries and cars as cargo) where the "free surface effect" can exacerbate a list and make the boat go from listing slightly to completely overturned within minutes. Modern safety provisions try to address the hazard, but may not be implemented on old ships.

In some regions with low safety standards or lacking inspections you should, if possible, check the ferry and loading procedures before deciding to use it. Some – or all – ferries may be in bad repair, made for sheltered waters but used on more demanding routes, or simply overloaded. If you cannot avoid such a vessel, at least plan for a catastrophe.

For ships in international traffic, the jurisdiction applied onboard is mostly the one of the flag nation, which may not be the one of the company or of any of the ports of call. If you have any law-related concerns, check. Usually, however, such third-country flags are flags of convenience; the flag country would probably avoid passing laws that could offend passengers without providing advantages to the shipowner.

Seasickness can be an issue for some individuals. If you are vulnerable – which most are in high seas and some types of swell – get medication and find a window seat.