"They're New Zealand fur seals," said Jo, as our boat bobbed on the turquoise water off Rottnest Island, near Fremantle. "They come here because the climate's better, there's lots of good things to eat, and the social welfare system is so good."
It was the second gratuitous Kiwi insult of the cruise ("This boat was designed in New Zealand, the land of adventure, but it was built in Freo so we know it was done properly"). It wasn't even as though the guide knew if there were any of us on board.
It was a fair bet, though: anyone visiting Perth is bound to do a day trip to Rotto.
Only 25 minutes by ferry from Fremantle, or 90 minutes from Perth, it's a low-lying, sandy island surrounded by water that's either fabulously clear, glowing turquoise or deep blue, and always warm. White curves of beaches are backed by snaggly limestone outcrops and green bush, the bays linked by roads that trail around and across the island.
These appear mostly deserted, because although there are clusters of accommodation at one end, there are no private vehicles on the island, which is a nature reserve: here, the cyclist is king. I was assigned mine without ceremony from the ferry as I arrived, and set off straight away to look for quokkas.
These native marsupials took the Dutch explorers by surprise in 1696 - "Rats the size of cats!" - and gave the island its name.
In fact, they are absurdly cute little creatures, their signature pose sitting up with their front paws tucked against their chests, and they weren't hard to find.
On the road above Porpoise Bay, four were hopping around under the picnic tables by the bikestands, boldly poking their noses into people's bags, clearly ignorant of the notices requesting visitors not to feed them.
The glamour of the white sand and brilliant water overcame even marsupial attractions, however: the warm Leeuwin current here leads to claims that there are 135 species of tropical fish to observe on the reefs, and at Little Salmon Bay lots of people were busily snorkelling. Somewhat wussily, I stayed close to shore.
"Always best to outrun a shark rather than try to outswim it," nodded another shallows-dweller. Happily, we saw only dolphins and the fur seals on our Eco Express circumnavigation of the island. Ninety minutes of exciting bouncing over the waves in the Kiwi-designed rigid inflatable was interspersed with gentle rocking as we observed wildlife that included ospreys and their improbable twiggy tower nests, one of which was 70 years old.
The seagrass meadows here underpin the marine life, and to protect them only 900 moorings are licensed; there's a a 10-year waiting list for a place. They are all well-used, and the island hums with people cycling, walking and swimming.
Also eating and drinking, of course, and as the Quokka Arms was crowded, I pedalled around to Geordie Bay to try the cafe there. Only the best chips ever.
The fish that went with them was, of course, barramundi - when is it not, in Australia? - but it was good too, although nowhere near as memorable as the chips.
Fuelled-up, it was back on the bike again, to cruise down a welcome hill and past a series of salt lakes, the water pinkish, their edges rimmed with foam, and beyond them the Wadjemup Lighthouse.
Built in 1896 and 20m high, it's a landmark, the white-painted stone stark against a blue sky.
White, blue, pink, turquoise, green: these are the colours of Rottnest Island. It's a beautiful place, and wonderfully peaceful, with nothing but the wind in the trees and mournful crows cawing.
Bouncing back across the sea to the mainland at the end of the day, the Freo Doctor of America's Cup fame blowing the ferry along, I was glad I'd gone. Insults notwithstanding.
The writer was a guest of Tourism Western Australia and flew courtesy of Air New Zealand.