As U.S. travelers may have difficulty booking cruises on Australian websites, where prices are listed in Australian dollars, cruise lines recommend using U.S. websites and U.S. travel agents. Keep in mind that fall in North America is spring in Australia and New Zealand. Most cruise ships sail to and around New Zealand from their spring through their fall.

Some cruise lines — Royal Caribbean, Celebrity, Holland America, and Princess — are marketing their Australian cruises in the United States, but Carnival is not, expecting to fill 95 percent of Carnival Spirit with travelers from Australia. All prices that follow are per person for two people in a cabin, and may not include some taxes and fees.

Royal Caribbean is advertising 14-night cruises from New Zealand and from Australia, starting at $1,100-$1,200 in an inside cabin, and $1,700 in a cabin with a private balcony. Cabins on Celebrity Solstice start at about $1,400 for a 10-night roundtrip cruise from Sydney to New Zealand; cabins with a balcony start at about $1,700.

One major impact from the cruise ship invasion of Australia and New Zealand are the itinerary choices, which never before have been as varied and rich. Royal Caribbean, a leader in marketing South Pacific cruises, says its three ships will offer 50 different itineraries to a total of 56 ports.

For travelers with a worldly bucket list, some of the itineraries are mesmerizing, including Australian ports such as Darwin and Cookstown, New Zealand ports such as the docks for Rotorua and sounds (fjords), as well as sailings to Tasmania, Indonesia, Papua New Guinea, Singapore, Hong Kong, and some far-flung South Pacific islands.

In January 2013, for instance, Voyager of the Seas leaves Sydney on a 14-night trip to Noumea, New Caledonia; Lautoka, Fiji; and New Zealand ports of Tauranga (Rotorua), Auckland, and Wellington. Prices start at about $1,700 for an inside cabin.

Holland America’s Oosterdam cruises for 10 days out of Sydney in January to New Caledonia and Vanuatu. Prices start at $1,400.

The Sea Princess in January has a 14-night round trip from Sydney that stops in Lifou, New Caledonia; Vila, Vanuatu; Port Denarau, Fiji; Suva, Fiji; Savusavu, Fiji; Dravuni Island, Fiji; and Noumea, New Caledonia. Prices start around $1,650.

Holland America and Celebrity are offering a circumnavigation of Australia, which will take a month. The Volendam’s 34-night circumnavigation starts Oct. 21, visiting the Whitsunday islands, the Great Barrier Reef, Lizard Island, Torres Strait, Darwin, Komodo (Indonesia), Perth, Adelaide, Melbourne, and Hobart (Tasmania). Inside cabins start at $3,500, a cabin with private balcony at $10,000. Celebrity Solstice’s 35-night circumnavigation of Australia and New Zealand leaves Auckland in February 2014, ending in Sydney in March.

Sydney sailings to Tasmania, New Caledonia and Australian ports, such as Melbourne, Brisbane and Cairns (gateway to the Great Barrier Reef), can be as short as seven nights, but cruises to New Zealand and farther northeast usually are longer because of the sea distance to cover. A circle of New Zealand takes a week or longer.

Cruises to New Caledonia, Vanuatu and Fiji are especially popular in the Southern Hemisphere’s winter (North America’s summer), when cruising New Zealand would be much colder.

Carnival Spirit arrives in Sydney in October to begin beach vacation cruises of 8-11 nights in the islands of New Caledonia and Vanuatu, with stops at Noumea, Isle of Pines, Poum, Vila, Santo, Wala, and Mystery Island. The Spirit will be based in Sydney, and Carnival already has announced 41 sailings from its homeport in 2014. Carnival Corp.’s lines will have seven ships sailing full-time in the region, including Princess and P&O Australia vessels, up from two in 2007.

David Molyneaux writes regularly about cruising. He is editor of TheTravelMavens.com