The law of diminishing returns is when the more you pay for something the less you get.
At a glance this might also describe to the pricing of cruise fares; the more you pay, the smaller your boat shrinks.
For as little as $75 a night you might book a berth on a 230,000 tonne Oasis-class pleasure cruiser.
Meanwhile on the modestly sized 184-passenger Le Lapérouse, you will be paying ten times that for a nine-day cruise round New Zealand.
Aboard her sister ships' more exotic itineraries, such as the 22-night Northwest Passage through the Arctic Circle, you could be shelling out $1600 a night on a voyage past the polar bears.
However, that's not to say bigger is necessarily better.
With typical Gallic charm, captain Jean Philippe Lemaire rebuffs the suggestion that the luxury cruise line is short-selling their customers.
"The idea is to use a small cruise ship with a friendly atmosphere," says the Le Ponant co-founder.
"Expeditions are our best segment," he says. "Mainly we are known for 'white expeditions' to polar regions."
He helped launch the company over three decades ago from the deck of the flagship Le Ponant, for which his company is named.
The unique three-mast sailing ship is still taking guests on luxury itineraries.
However Captain Lemaire has overseen huge growth in the company – if not the capacity of the vessels.
Le Lapérouse is the latest addition to the company and the first of six explorer-class vessels being built. All under 300 passengers.
These so-called "explorer" vessels are designed with adventure in mind. Each one will be visiting the off the beaten-track destinations to provide luxurious isolation.
And then there is Le Commandant Charcot, which will be taking passengers from 2021 on Arctic expeditions to the absolute polar north.
"I've been many times in the Arctic but Le Commandant is a true ice breaker, meaning it will be a good tool to show the North Pole to guests."
The expeditions are a highlight for both guests and crew.
"It's the best way for any way for a captain to keep his motivation," says Lemaire.
It is hope the adventurous itineraries to exotic locations such as the Orinoco Basin and
west Africa's Bijagos Islands will attract high-paying guests.
For her modest size, she packs a lot of luxury per square inch.
The cabins are designed by French architect Jean-Phillipe Nuel and spa treatments are on offer from renowned Parisian beauty house Sothy's.
A butler service is also included for passengers traveling in the suites on deck 6.
There is just the one restaurant on deck four. Like every one of her features, the Lapérouse's 260-square-metre dining room is chic, elegantly proportioned and proudly delivered with an authentic French accent. Although the cupboards were bare on arrival to Auckland – having been recently raided by MPI biosecurity – there is no chance that passengers of Le Lapérouse will starve.
There are only three bars on board, although champagne flows freely. The most outstanding of these is discovered below the waterline, in the atmospheric Blue Eye lounge.
Looking out into the depths are two panoramic portholes, resembling eyes.
Although there was not much to see though the 42cm-thick glass apart from murky Auckland harbour water, the overall effect was spectacular.
The belly of the whale, this sub-sea bar is fitted with under-seating speakers which vibrate with the sound of the ocean.
However for the luxury liner with luxury price-tags, what guests are most interested in is not found onboard.
Passengers would rather spend less time on a floating sun lounger and more time in the field exploring the overland excursions.
The great advantage of these explorer vessels is the array of excursions to intimate and unspoilt destinations, made possible by the unobtrusive size.
What guests are paying for is freedom.
On the top deck are a fleet of dirigible zodiac motorboats, which carry passengers to shore excursions on deserted desert islands and polar glaciers.
In close proximity to wildlife in remote places, guests are made to feel like presenters of their own National Geographic feature. Which is convenient, as one of the cruise line's partners is the famous photography magazine, which is leading five expeditions this year on Lapérouse and four of her sister ships.
It is an added excitement for guests to rub shoulders with photographers and naturalists, who will also be presenting guests lectures while onboard.
For this small vessel with high prices, there is a certain French swagger. Within a small package, the Lapérouse carries its luxury title with confidence, as if to say "it's not the size that matters, but how you use it."
• For more information, visit Le Ponant's website.