A is for ash - the volcanic variety, which has spurred a sea change in our attitude to terrestrial transport. The six-day lockdown of European airspace has prompted upwards of one million people to turn to maritime alternatives. This will accelerate a trend begun last year: the number of airline passengers from UK airports slumped by 10 per cent in 2009, but ferry journeys increased.
Even on the busiest sea routes in Europe, between Dover and the French ports, you can rediscover the joy of ferry travel: perhaps inspired by the UK Foreign Secretary's invocation to 'head for Calais', plenty of homebound Brits have this week experienced the elation of seeing the White Cliffs of Dover hove into view on the journey back to Blighty.
Yet ferries are far more than a means to an end: many European sea journeys are adventures in their own right.
From the Aran Islands of Ireland, or the Western Isles of Scotland, you can plan a journey with plenty of ferry options to the furthest-flung archipelagos of Croatia and Greece.
Let this manual of maritime magic inspire you.
A great way to start a lexicon of the waves, because the city has an excellent free ferry starting on the north side of Centraal Station, across the IJ river, which provides an excellent perspective on the city.
And it is also accessible from the UK by a pair of overnight ferry routes that provide a civilised approach to this most human of cities.
Britain's last-surviving Continental Boat Train departs from Liverpool Street station in London each evening at 8.38, and represents one of the best bargains in rail-and-sea travel. The journey from London, or any station in East Anglia, to Amsterdam or any station in the Netherlands, is £29 (NZ$62) each way - plus the cost of a berth if you take the night service between Harwich and Hook of Holland. Stena Line offers comfortable accommodation and carries cars as well as "rail and sail" passengers. This month the route gets the first of two £200m "superferries", complete with internet.
The other way to go Dutch by sea is on DFDS Seaways, which sails overnight between Newcastle and Amsterdam. This is an illustration of a maritime "Ryanair effect": the vessel actually sails between North Shields and the North Sea port of IJmuiden. But connections to Amsterdam are straightforward by rail or road.
A more attractive town than Calais from a tourism perspective, with a fascinating Old Town, superb seafood, and a new connection on the rapidly expanding LD Lines. There are ferries every six hours or so from Dover.
Nowhere else in Europe is the role of ferry as lifeline better illustrated than in north-western Scotland. Caledonian MacBrayne is a heavily subsidised operation, offering regular, usually reliable links between the mainland and the Western Isles. Ordinary fares are high, but for the tourist there is are "Island Hopscotch" tickets that offer options for driving (or cycling) on a range of routes.
Dunkirk is served by ferries every two hours (less frequently at weekends) from Dover on Norfolkline. The ferry company normally insists that passengers have a mode of transport from a bicycle upwards, but this week has been operating coaches for the benefit of stranded airline passengers - and, unlike its rivals, the service is free.
The Baltic republic with flourishing links across to Helsinki, the best ferry-connected two-centre city-break in Europe. You can sail from the capital, Tallinn, to Helsinki in a couple of hours with a passage booked through an agent such as Direct Ferries - a journey between the two most handsome cities in the Baltic.
Tragically, Estonia was the name of the ferry that sank in 1994 while sailing between Tallinn and Stockholm, with the loss of 852 lives. As with aviation, the development of ferry safety is written in blood.
In fact, most travellers pay fares that are far less per person. The ferries took one heck of a beating from the more nimble no-frills airlines until they adopted the same dynamic, demand-sensitive pricing model. And what does that mean? If you take an off-peak sailing on Norfolkline between Dover and Dunkirk, you could pay as little as £19 each way for a car and four passengers; but if you book late for a morning sailing on a summer Saturday, the price could be five times higher. Interestingly, you can counteract this - if you are a late booker n by buying a carnet of journeys, as offered by SeaFrance, with individual one-way journeys available for as little as £32 each way.
A very special case, in every sense. Island-hopping around the eastern Mediterranean is about as rewarding as it gets, but be flexible when you contemplate some Aegean ambulation. A web of ferry, jet-boat and hydrofoil services operated by competing companies links the islands with each other and the mainland. The island-hopper's bible is the Thomas Cook Guide to Greek Island Hopping by Frewin Poffley.
The book contains schedules for every route, but Poffley observes that the region "is not noted for achieving Germanic standards of timekeeping". Be prepared for your planned itinerary to fall apart n and beware the sudden Aegean squalls. On what appears to be a brilliantly clear and calm day, the sea can swell quite suddenly and render disembarkation impossible at some exposed ports; the ferry will steam on to her next destination.
They were big in the Eighties, but almost all services ceased in the Nineties n the high fuel consumption proved unsustainable, and eventually Hoverspeed abandoned these remarkable craft. If you want to experience one, you can go anywhere you like so long as it is the ...
ISLE OF WIGHT
A hovercraft still flies between Southsea in Hampshire and Ryde on the island in 12 minutes. A return fare is £17 with Hovertravel. Traditionally, fares to the Isle of Wight from Wightlink and Red Funnel have been some of the highest, per mile, in Europe. But competition is set to increase, thanks to a new promotion between Greyhound, Hovertravel and Southern Vectis that promises to cut one-way fares from London to the Isle of Wight to an average of £14. Incidentally, buses from Victoria to Southampton end their journey just across from the Red Funnel terminal.
Remember Marshal Tito? The Yugoslav dictator was big in the Eighties, before his federation fell apart after his death. One of his lasting contributions was a flourishing ferry company, Jadrolinija, which operates along the coast of what is now Croatia and links the many islands strung out offshore.
The Orkney capital is the hub of the Northern Isles' ferry system. You can reach it from Aberdeen on NorthLink, or - with a much shorter sea crossing - from Scrabster near Thurso to Stromness on Orkney.
Le Havre was once the illustrious gateway to the world, with much of the French shipping industry based there. But it was ravaged in the Second World War. The reconstruction has been mostly in concrete, which looks impressive in a brutish sort of way. For many, Honfleur, on the southern (left) bank of the Seine, is more appealing; you can reach it over a spectacular bridge. Le Havre is connected by a new fast ferry, taking only three hours, 15 minutes, from Portsmouth with LD Lines.
MANCHESTER SHIP CANAL
For most of the time, Mersey Ferries shuttle across the water between Liverpool and the Wirral. But the summer series of cruises along the Manchester Ship Canal from Liverpool to Salford Quays begins on Thursday. Further sailings are approximately weekly in May, June and September, and twice a week in July and August. The one-way fare for the six-hour, 35-mile trip is £36.
NATIONAL FERRY FORTNIGHT
National Ferry Fortnight, starting on May 8, is designed to persuade us of the joys of maritime meanderings. Expect incentives to book for your summer holiday.
Ouistreham is the port for Caen in northern France, served from Portsmouth by Brittany Ferries. O is also for Ostend, linked from Ramsgate by LD Lines.
Pride of Bilbao, Pride of Calais and Pride of Dover: all once the prides of the P&O Ferries fleet, but all are to sail off into the sunset. The link from Portsmouth to Bilbao will cease in September. The Calais and Dover prides are to be replaced, starting in December, with the biggest ferries ever seen on the Channel.
Quiberon is the ideal base for Breton island-hopping. This pretty port lies at the end of a peninsula south of Lorient and west of St-Nazaire. Ferries seasonally sail from here to Ile d'Houat and Le Palais, which feels like France 20 years ago.
You can reach the region on Brittany Ferries, which has services from Plymouth to Roscoff and Portsmouth to St-Malo.
Brittany is also the location for the most exciting ferry development in Europe this year: a new link from the port of St-Nazaire to Gijon in the beautiful Spanish province of Asturias. This cuts a long, drab drive through France, and opens up possibilities for trips via Brittany to northern Spain, returning from Santander to Plymouth or Portsmouth.
If you would like to add even more sophistication, then build in a stop in the Channel Islands: Condor Ferries has a network from Weymouth, Poole and Portsmouth to Guernsey and Jersey, with links to St-Malo.
Ferries still operate along and even across Western Europe's leading waterway. KD Rhine is the main operator, with plenty of ferries from its base in Cologne. The KD Rhine Pass allows travel between Bonn, Cologne, Koblenz and Mainz.
Seasickness is becoming less of an issue as stabilisation systems get more sophisticated and ships get larger. Nevertheless, if you suffer from motion sickness, try to find the part of the ship where movement is minimised and stabilise head movement by bracing it against a fixed object. Fix your gaze on the horizon.
Timing is everything, at least on the airlines: fail to meet the check-in deadline, and you usually lose your flight and your money. The attitude of most high-frequency shipping lines could hardly be more different. From Dover, Norfolkline (to Dunkirk), and P&O and SeaFrance (to Calais) generally have plenty of capacity, and usually take the view that if you arrive in time for an earlier sailing they will allow you on board, and they also prove lenient if you miss your booked sailing.
Ulysses is the world's largest and most reliable car ferry, at least according to Irish Ferries; the ship, named after the James Joyce character, operates on the Holyhead-Dublin route, carrying nearly 2,000 passengers. Irish Ferries also operates from Pembroke to Rosslare. Its major competitors across the Irish Sea are P&O from Troon and Cairnryan to Larne, Norfolkline Irish Sea Ferries from Liverpool to Belfast; and Stena Line, which sails from Fishguard to Rosslare and from Holyhead to Dun Laoghaire n ironically, the location just outside Dublin where the opening of Ulysses takes place (specifically, the Martello tower in Sandycove, from where you can watch the ferries arrive and depart).
One other choice across the Irish Sea: the Isle of Man Steam Packet Company goes from Liverpool or Heysham to Douglas, and on to Belfast or Dublin.
The southernmost destination in Europe that you can access by ferry and the smallest capital of any EU state. The easiest route from the northern Mediterranean ports is from Genoa to Palermo, the Sicilian capital. You then cross the island to Pozzallo, from where ferries depart to Malta.
Whales and dolphins can be seen from many ships in Europe, but a couple worthy of note are P&O from Portsmouth to Bilbao and DFDS from Newcastle to Amsterdam, who often deploy wildlife officers on board to help spot cetaceans.
X-rays are part of the misery of airport security. Ferries are less susceptible to terrorist outrages, and car drivers and passengers face no checks n but on international journeys from Britain foot passengers still have to pass through metal detectors and have their bags checked by X-ray. The restrictions that airline passengers face on hazardous substances from toothpaste to tequila do not apply.
Yachts under sail take precedence over ferries under steam, but in practice both try to avoid each other. The radar systems on the bridge of a modern ferry are spectacularly sophisticated.
Zeebrugge, a lovely Belgian resort, which also provides the Continental end of the only ferry direct from Scotland to Europe - with Norfolkline. It is also served by P&O North Sea Ferries from Hull, which also runs to Rotterdam. You can reach Bruges in 15 minutes by train or car, sip a beer and toast your good fortune for going by boat.