Cruising might be more popular than ever, but there are still plenty of travellers who have yet to discover the joys of a holiday at sea.
The perks are plenty, from the variety of places you can visit to the convenience of touring the world but only unpacking once.
Just as there are big resorts and boutique hotels, so there are ships large and small, budget and luxurious.
So, where to start? When it comes to cruising, size is everything. There are ships that hold just 50 people, and floating cities with more than 6000 passengers - and every size in between.
You need to decide which you like the sound of and where you fancy cruising
One Size Fits All - Beasts of the Ocean
Their biggest ships hold 4000 to 6000 passengers and have everything from pubs to posh restaurants, climbing walls to water slides.
You'll find NCL and Royal Caribbean ships in Europe, the Caribbean, Alaska and Asia, while Carnival sails the Caribbean and Alaska.
Choose P&O's Britannia to cook with TV chefs James Martin, Eric Lanlard, Atul Kochhar and Marco Pierre White. Princess ships sail all over the world; P&O Cruises sail mainly from the UK to the Med and Northern Europe in the Europeon summer.
Later in the year, it has ships in the Caribbean and sailing around the world. Disney Cruise Lines' two biggest ships, Dream and Fantasy, sail the Caribbean.
You'll be cruising with 4000 others, but who cares when you can watch Disney films and meet Mickey himself. Come summer, Mickey and chums also sail in the Mediterranean on the smaller Disney Magic.
For a mid-size ship - 2500-3000 passengers - consider Holland America Line or Cunard, or downsize even more with Fred Olsen Cruise Lines (fredolsencruises.com), Cruise and Maritime Voyages and Thomson Cruises. Thomson's biggest ship holds just over 1800 passangers.
Holland America ships sail all over the world, even to Antarctica. Choose Cunard for world cruises and transatlantic crossings between Southampton and New York.
Oceania Cruises and Viking Ocean Cruises have ships for 1,250 and 930 passengers respectively, or choose Crystal Cruises' luxurious Crystal Serenity and you'll be sharing with just over 1,000 other passengers.
As a general rule, the smaller the ship, the more luxurious the cruise line. The passenger count on Saga Cruises, Regent Seven Seas Cruises, Seabourn, Silversea and Hapag-Lloyd Cruises is in the hundreds.
Saga sails from the UK; Oceania, Crystal, Regent, Seabourn, Silversea and Hapag-Lloyd have ships in Europe, the Caribbean, Asia and South America; Viking sails in Europe and the Caribbean, and is launching its first world cruise in 2017.
Star Clippers has three tall ships for 170 to 227 passengers in the Mediterranean, Caribbean and Asia; swanky SeaDream Yacht Club has two yachts that sail the Med and Caribbean with just 112 people on-board.
Alternatively, you can take your cue from the Queen and cruise on Hebridean Islands Cruises' luxurious Hebridean Princess. It carries just 50 passengers.
No Noisy Kids!
Cruise and Maritime Voyages sailings are almost exclusively for those aged over 16, while Fred Olsen Cruise Lines has several departures just for adults aged 18 or over.
P&O Cruises ' ships Arcadia and Oriana are reserved for those aged 18 or over, and Viking Ocean Cruises allows only children aged 16 or over on its ships. You have to be 50 or over to sail on all Saga Cruises ' voyages, but a companion can be aged 40 or over.
When to Travel
Cruise ships follow the sun, so in winter you'll find them in the Mediterranean, Baltic, Norwegian fjords and the Caribbean.
Come summer, ships sail from Europe to the Canary Islands, but most head to the West Indies, sailing the Caribbean from Miami, Fort Lauderdale and Barbados. January and
Asia, Australia and Central, the South Pacific and South America are also summer hotspots.
Where to Go?
The British favour the Med because it's close and offers such variety. But there are so many other places to visit by ship. The Norwegian fjords have majestic snowy mountains. Go in winter to see the mysterious Northern Lights.
For a city extravaganza, a classic Baltic cruise visits Copenhagen, Stockholm, Helsinki and Tallinn, the capital of Estonia. And most ships also stay two days in St Petersburg.
A cruise is easily the best way to see the Caribbean, as you visit so many islands on just one holiday.
If adventure appeals, cruise the Galapagos Islands and get up close to booby birds and giant tortoises. Or take on the Drake Passage - a treacherous stretch of ocean between Cape Horn and Antarctica - to walk among penguins with an expedition cruise line such as Hurtigruten.
Life on the River
River cruise vessels are smaller (around 150-200 passengers), have fewer facilities, and itineraries generally do not include any days at sea.
Instead, there are port calls each day and time to sit back and enjoy the sights as life unfolds along the river bank.
The Rhine is a favourite for its fairytale castles, but the Danube delivers the fabulous Vienna and Budapest. Choose the Rhone for wine-tasting in Provence and the Douro in Portugal for port wine.
Cruises on the Mekong, Irrawaddy, Ganges and Yangtze with companies including Viking, AmaWaterways and APT are a great way to learn about Vietnam, Cambodia, Myanmar, India and China.
Swish Cabin on the Cheap
Look out for free upgrades advertised in the travel pages of the weekend papers.
Book a "guarantee" cabin rather than picking a specific room or location on the ship. You are guaranteed the cabin category you have reserved - but if none is available on embarkation, you'll be upgraded.
Find your favourite cruiseline, join the loyalty scheme and book lots of holidays. Hopefully, you'll be first in line if an upgrade comes up.
Or book with a cruise line you have never travelled with. They might upgrade you to win your loyalty.
Cruise outside peak times. When demand falls, prices go down, too.
The Best Time to Book?
If you know the date, cruise and cabin you want, book early. The same goes if you want a single cabin, as they are in short supply.
But if you can be flexible, hang on, because competition means there are great deals all year round. It might be a discount, or perks such as free flights or drinks, no gratuities to pay, or free excursions.
Book with a specialist cruise agent for the best advice and attractive deals from a variety of cruise lines.