Cruising is more popular than ever. In 2015, more than 23 million people took a cruise. They’re lucrative too – statisticbrain.com revealed that vacationers spend on average $500 (£382) more a week on a cruise than on any other holiday. As some ships become larger and others specialize (there are Disney-themed voyages, Elvis tributes and knitting cruises), others become grander – such as these five cruises for those for whom money is no object.

Silversea Cruises is an Italian family-owned company that specializes in intimate, deluxe ships. Its World Cruise 2017 starts from San Francisco in January and incorporates 62 ports in 25 countries over 116 days.

Sailing aboard the Silver Whisper, a boutique ship for 382 guests, all suites have an ocean view and a personal concierge. Extras such as business-class flights and exclusive trips are included.

To enjoy three sumptuous months at sea, you’ll need to hand over at least $54,784 (£41,786). This is the cost, per pampered guest, for a Vista Suite. Expect to sleep in the finest bed linens but don’t anticipate a balcony – you need to spend more for outside space.

The most expensive option – the two-bed 1,264 square foot Owner’s 2 Suite – has a large teak veranda to lounge on, multiple marbled bathrooms, and includes dinner at the officer’s table. All this and more for a cool $202,173 (£154,168) per guest, minimum.

Still regarded as the most expensive cruise ever created, the Million Pound Cruise (that’s around $1.3 million) was crafted by UK company Six Star Cruises, who described it as “the world’s most luxurious 124-day vacation”.

The cruise sailed in 2013 and cost around £1 million per couple – that’s £8,000 ($10,490) a day.

The opulence didn’t start on the ship. Guests began with a Beluga Caviar and Champagne-fueled helicopter transfer to the airport followed by a private jet to the USA with catering by a Michelin-starred chef. Transfers Stateside were in a Rolls Royce Phantom to a Beverly Wiltshire hotel suite (pictured) in LA for four nights before embarking.

Staying in a 1,000-square-foot Royal Suite on Silversea’s Silver Whisper, guests on the Million Pound Cruise spent 115 days on board sailing around the world.

The ship visited 28 countries: French Polynesia (such as Tahiti, pictured), Australia, Malaysia, Vietnam, Madagascar, Africa and the Caribbean were some of the far-flung places witnessed.

For months passengers experienced stunning views and special shore excursions, relaxed at the Mandara spa, enjoyed live entertainment in the theater (pictured) and fine dining, and passed the time at events such as talks and wine tasting – all in a child-free environment.

When the cruise pulled into its final port, Fort Lauderdale, guests were taken to an exclusive $9,572 (£7,300) a night villa in Miami to become reacquainted with being landlubbers again.

Cruising isn’t just about indulging, it’s about once-in-a-lifetime experiences. National Geographic Expeditions offer trips around the world, from Portugal to the Polar regions, that enable guests to embrace the natural world.

Expedition ships such as the National Geographic Explorer are smaller and ice-class in order to cope with challenging weather and topography.

The Explorer sleeps 148 guests in 81 cabins, all with sea views. There are the usual cruise comforts: a lounge, library, and a spa, sauna and fitness center. Then there are more unusual extras, such as Zodiac landing crafts, kayaks and specialized video equipment so guests can get up close and personal with nature.

National Geographic’s dearest option is the 24-day Epic 80°N around the high Arctic. Starting and ending in Iceland, the trip follows the little-explored northwest Greenland coast, takes in the coastal beauty of Ellesmere Island and Baffin Island (pictured), and ventures in to Lancaster Sound – the gateway to the legendary Northwest Passage. Instead of seeing the sights at touristy ports, passengers witness gargantuan icebergs and polar bears, walruses and whales.

Seeing flora and fauna this wild comes at a price. The cruise starts from $25,990 (£19,831) per person (more for single occupancy) and goes up to $49,640 (£37,872) for the best cabins. This doesn’t include airfares to Iceland. The next one is in August 2017.

Christened by Her Serene Highness Princess Charlene of Monaco on July 13 2016, Regent’s Seven Seas Explorer is currently hailed as the most luxurious cruise ship ever built. This picture shows it being built at Fincantieri shipyards in Sestri Ponente, Italy.

Costing an eye-watering $450 million (£344 million) to build and fit out, there are no paltry cabins on this opulent ship – it’s suites all the way – while the Deck 11 pool deck (pictured) boasts impressive views and attentive crew to cater to your needs.

The Seven Seas Explorer is nothing short of palatial. High ceilings, sweeping staircases, stone floors flecked with gold leaf, and crystal chandeliers adorn public spaces – there’s even a $500,000 (£382,000) bronze sculpture and specially commissioned artwork.

The breakfast buffet has a self-serve caviar station and there are 400 Versace place settings in the Compass Rose restaurant (pictured). Foodies can take classes in the culinary arts kitchen or take exclusive gourmet explorer tours on land.

The luxury extends across the ship and into the Canyon Ranch SpaClub, a stunning spa that rivals ones at sea and on land. There’s a dramatic infinity plunge pool (pictured), heated ergonomic loungers, a full-service salon and unique ocean-themed treatments – all fashioned to the highest standards.

Luxury cruise companies will always try to outdo each other on accommodation but Explorer’s Regent Suite arguably takes the crown. All suites boast oversized balconies and complimentary chilled Champagne, but the Regent Suite is astounding. At 4,433 square foot (including the balcony) it’s the largest suite at sea with 270-degree views over the bow of the ship. Guests sleep in a $90,000 (£68,800) bed and can tinkle the ivories of a $250,000 (£191,000) Steinway piano.

The Regent Suite also has its own in-room spa – another first – with unlimited treatments, and a private garden. Guests get a private car and driver at every port too.

According to Bloomberg.com, Regent is regarded as the most expensive luxury cruise brand. This is because almost everything is built in to the price – from flights and shore excursions to drinks and gratuities. Bloomberg guestimates a price tag of $1,000 (£764) per person, per night, though the breathtaking Regent Suite will set you back $10,000 (£7,640) a night.

Best known for its transatlantic crossings, the Queen Mary 2 is the grande dame of ocean liners and the epitome of elegance. In 2016 it was refitted, returning as Queen Mary 2 remastered.

It comes as no surprise that the Queen Mary 2, or the QM2 as she’s also known, has fans among the rich and famous. The New York-Southampton voyage is especially popular as a deluxe alternative to flying. HM The Queen, Hillary Clinton, Beyoncé and Sting have all sailed on the ship, while the esteemed film director Francis Ford Coppola (pictured) was captured on Instagram during the eight-day transatlantic crossing on the newly remastered ship.

Cunard’s flagship is renowned for having some of the plushest suites on any cruise liner, of which the Queens Grill and the Princess Grill suites are the grandest. The Grill suites are ‘personal enclaves of luxury’ that grants exclusive access to the Grills lounge, sun deck and dining rooms (pictured).

The duplex suites have 2,249 square feet of space with beautifully-appointed bedrooms and marble bathrooms on the upper level and stylishly-decorated living space and another bathroom on the lower level, connected by a sweeping staircase. There’s also a private gym area and balcony. Whilst the other suites have access to a concierge, guests at the Queens Grill also have their own personal butler.

Passengers don’t get such attentive service and understated opulence for peanuts. A round-the-world trip in a Queens Grill suite can cost up to $183,000 (£138,000) – that’s more than $1,600 (£1,200) a night, making it one of the priciest cabins on the water.