For curious adventurers seeking out the furthest-flung corners of the globe, private transportation options are limited.
Superyachts require re-fuelling long before reaching the most remote Pacific islands.
Tempted to explore the North Pole on foot?
Your private jet will need to find a landing strip first.
For the modern-day Ulysses, there will soon be alternative means of getting away from it all - in an airship.
Harking back to a golden era of 1930s air voyaging, a handful of companies is readying private airships complete with luxurious bedrooms, open-air viewing decks, transparent flooring and even space for a submersible.
Wary of the shadow cast by the 1937 Hindenburg disaster, these rigid ships are filled with non-flammable helium, not hydrogen.
Most are still in the conception stage. Halo is a residential airship dreamed up by London-based studio Andrew Winch Designs, with a living area the size of four football pitches comprising 20 bedrooms, a spa, a cinema and a ballroom.
If it sounds like science fiction, think again.
A 266ft-long prototype made a test flight four years ago and received certification by the US Federal Aviation Administration.
Andrew Winch reckons the vehicle - estimated to be worth US$330 million (S$451 million) - will be ready in a decade.
Close to production is US defence giant Lockheed Martin's vehicle, the P-791 Hybrid Airship, and the UK's Straightline Aviation Hybrid Airship, which last year signed a US$480 million letter of intent to deliver a dozen.
Dragon Dream, built by Worldwide Aeros Corp, was granted airworthiness after its first tethered flight in 2013.
However, cargo and industrial usage, rather than well-heeled passengers, are the targets for these firms.
The Airlander 10 from Hybrid Air Vehicles could get off the ground as early as 2018. It has been positioned as a 'superyacht in the sky'.
At 92m-long, she can fly at 100mph for up to five days at a time, on around a quarter of the fuel a plane would use.
The Airlander is a 'hybrid' of an airplane and an airship - it gets 40 per cent of its lift from the aerodynamic wing shape, and 60 per cent from the helium fill - it is therefore inherently more efficient than other forms of air transport.
It marks a paradigm shift in low-carbon air travel, according to Steve McGlennan, chief executive of HAV.
"There's an understandable default view that airships are old-fashioned because they were prominent in 1930s," he says.
"But electric cars were big in the 1930s too and they've come back again. Airlander will be the Tesla of the air."
After several successful test flights over the Bedfordshire countryside and despite one well-documented 'hard' (read, crash) landing last year, 2,000 shareholders have poured US$25million into HAV.
In addition a US government contract provided over $90 million of funding and the company has received around $10 million of UK and EU grant funding.
Investors range from industrialist billionaires through to aviation enthusiasts who have participated through crowd funding.
Well known shareholders include Bruce Dickinson, lead singer of the band Iron Maiden.
"They're motivated by the fact that this is an environmentally friendly, low-emission vehicle that can currently lift a 10-tonne payload with the potential to lift 1,000 tonnes," says McGlennan.
"The uses are myriad, from a surveillance platform to a communications hub, to a means of reaching inaccessible disaster zones; it can drop its payload exactly where it is needed."
Separately, two other billionaires are interested in using Airlander for their private voyages.
"They want something over and above what their friends and peers have," adds McGlennan. "They want a superyacht in the sky."
Airlander 10's blueprints show sleek interiors, hotel-style ensuite bedrooms, a luxury daytime area with dining rooms, bars, and internal and external viewing decks on a hanging gondola. "The world is really your oyster, you could have a kitchen fitted out for a Michelin-starred chef on board," says McGlennan.
"Our initial discussions with our two separate billionaire clients envisage eight guests each with their own bedroom and a similar number of staff."
It will feel more like journeying by train than air.
Silently, slowly gliding between 4,000-7,000ft, turbulence will be minimal and passengers will breathe fresh air, not canned oxygen, in a pressurised cabin.
And because the engines are never less than 17m away, vibrations are imperceptible.
"Back in the 1930s airship era, they would play a game where they'd stand a pencil on its end and see how long it would take to fall," says McGlennan.
But the game stopped as the pencil never fell.
Of course, any good superyacht comes with a roster of toys, and Airlander 10 will be able to capture and release a private jet with a trapeze mechanism, just like the US Navy airships Akron and Macon did in the 1930s.
It will also be able to carry personal watercraft and submarines, such as the Deepflight submersibles beloved by venture capitalist Tom Perkins, Sir Richard Branson and Redbull owner Dietrich Mateschitz.
But an airship's real selling point is the freedom it allows: freedom to land in the desert, snow, tundra, ice or water, indeed, almost anywhere. Because it is filled with ultra-light helium it only weighs one tonne - its cushioned undercarriage and its low density means there is no impact on landing so you don't need a runway. To buy an Airlander will cost around US$40 million, in line with the that of a sizeable business jet.
When avant garde technology meets sky-high budgets, fantasy can become reality.
For his final year University design project, Mac Byres conceived of an electric airship he called The Aether.
"It is a luxury cruise concept based upon an airship platform. This allows passengers to travel at high speed in complete luxury, while providing guests with the most breathtaking views available," says Byres.
His inspiration may surprise you. "For the exterior I looked at things that appeal to the young adult generation, who will be the target market for The Aether. Things such as: Thunderbird 2, Star Wars Naboo Royal Starship and NASA's Space Shuttle."
He wanted to communicate the green credentials of the all-electric Aether, by using clean colours and forming the main balloon into a more aerodynamic and wing-like shape. Byres has also designed an airship called Hemera, designed to land solely on water, which he aims to unveil at Expo 2020 in Dubai.
"We're hoping to bring about a renaissance in airship travel and technology. The second phase of our plan is to expand the product line to create humanitarian aid stations all based on this re-born technology," he says.
Could Hemera or Aether become a reality? HAV wants to emulate the Aether ethos.
"We think [the Aether concept] gives a good idea of what the billionaire customer will want. We can deliver this level of experience in Airlander," says McGlennan.
Airship travel will create a new paradigm in experiential adventures, concludes McGlennan.
"The next few years will open up experiences in places where no tourist has ever dreamed of going."
This article was first published in BLLNR.