What also became clear was that the destinations hardly mattered. On a previous river trip of ours, an American from the travel trade had carefully explained that the cruise was the destination and this was illustrated perfectly on this voyage of the Royal Caribbean company's Radiance of the Seas.
Most of the guests, as the company calls its passengers, had boarded in Honolulu and were going to Sydney, a journey which takes 18 nights. The port calls amounted to five days with the rest of the trip being spent at sea, which meant a great deal of time in which the ship was the entire world.
But we grew to see why that world has such an appeal. Ships built on this heroic scale are unreal - almost surreal - environments completely removed from everyday life.
We had had a foretaste of the shape of things to come in our hotel at Honolulu, the Hilton Hawaiian Village. Some village. Our room was on the 35th floor of one of four tower blocks overlooking the charming Waikiki beach - and that was only one hotel.
But we were still staggered as we approached the Radiance of the Seas. It is vast, at 90,000 gross tonnes and 13 decks, and the cruise veterans beggared our imaginations with tales of two other ships in the company's fleet more than twice as big, with such implausible delights as aquatic shows and ice-skating displays.
Radiance was impressive enough for us. It featured glass elevators that travelled down the outside and inside of the ship. The main dining rooms, seating 1200, were like something out of those 1920s Hollywood movies set in ritzy hotels, and there are half a dozen other dining options from Mexican to Italian.
I thought of having a drink in every one of the places you could get one, but it would have turned into something of a Dunedin scarfie pub crawl with similar consequences and, even after 13 days (we disembarked in Auckland), I'm not sure I tracked down all the watering holes.
The theatre, which seats 850, would put most Auckland venues to shame and the gymnasium would have left your neighbourhood sweat factory for dead.
All this - and I could keep dropping mind-blowing statistics for a lot longer - provides a playground in which boredom is a dirty word. If you choose, every day can be crammed with activity. For most passengers, the day started with a look at the Cruise Compass, listing the day's potential engagements. A typical day's contents starts at 6am and ends at 1am and has more than 70 entries.
It was pretty exhausting just thinking about what you could cram in.
Should I go down the physical self-improvement path? A bit of work on the abs followed by chi kung "internal energy cultivations"? What about taking up bridge or ballroom dancing?
A couples massage class received the thumbs down but a lecture on one of the great naval battles of the Pacific scooted in, followed by watching on-board artist Des Spencer creating one of his Sydneyscapes.
Taking a break in the central concourse was like standing at a busy crossroads with a constant stream of people heading off for their next assignment.
If it is true that shopping is the West's preferred leisure activity, then the ship avoids consumption deprivation with its own arcade, claiming tax and duty savings, and daily specials offering deals from cameras to jewellery and art auctions.
This was, I confess, all a bit much for me. I dislike shopping on land and I wasn't going to start at sea. My idea was to spend a lot of time sitting around reading with an occasional glance at what was happening in the blue vistas of the Pacific.
In days and days at sea, I saw two ships on the horizon and three flying fish. But if nature failed to put on much of a show, except on our wonderful French Polynesia stops, the people-watching was never less than entertaining.
Because the trip started in Honolulu, we had assumed most of the passengers would be American, but Australians provided the overwhelming majority and they came in all shapes, styles and sizes.
I was particularly taken by one ponytailed and tattooed character whose artificial leg carried Harley Davidson tattoos.
But one of our dinner companions was a softly spoken former adviser to a succession of Australian Prime Ministers.
The dinners were one of the fixed points of the day and a couple of formal evenings gave those so inclined the chance to break out their gowns and tuxedos.
Not much opportunity for that on an Airbus, nor would any other form of travel supply the bizarre sight of a choir of waiters from 60 nations singing O Sole Mio - with not an Italian among them.
It would be hard to deny that food occupies a great deal of attention. There is the opportunity to eat almost around the clock and not a few seemed to be taking every advantage of that.
Greedy as I am, I gave up the challenge and occasionally passed on lunch, making do with the great roast beef rolls available at the Solarium covered pool where the morning swim started what became our regular routine.
I was never quite clear of the detail of how the rest of the day vanished before it was time to check out the evening's theatre show, a varied line-up strong on veterans but with some real talent on show.
Before we sailed we were not at all sure how we would go, starting our cruise career with a lengthy voyage and not much land.
But as we approached Auckland we were rather dreading the thought of leaving this bubble of unreality. Do our own meals? Make the beds?
Would anyone notice if we stayed on board until Sydney?
CHECKLIST
Further information: Royal Caribbean International operates Radiance of the Seas and Rhapsody of the Seas, from New Zealand and Australia this season and next.
An identical itinerary to that described here, but in reverse, from Sydney to Honolulu departs on April 5 at prices from A$3145 (NZ$4100) a person to A$13,455 for a royal suite.
Other itineraries vary from seven nights from Sydney to New Caledonia and return to 34 nights around Australia to Bali and New Zealand.
Guide prices are from A$1595 for seven nights in an interior cabin to A$6045 for a royal suite and from A$6050 for 34 nights in an interior cabin to A$25,300 for a royal suite.
John Gardner travelled courtesy of Royal Caribbean International.
