But it’s counter-productive to add several thousand extra miles to your overall trip in order to save a few hundred miles on the final leg of it.
Although the South Pole is due south from everywhere, if you follow a magnetic compass not only will you not end up at the Pole but you won’t even end up in Antarctica! Magnetic poles wander about a bit, and the South Magnetic Pole’s currently taking a refreshing tour of the Antarctic Ocean. Strange but true. (A gyro compass is a better bet.)
That is basically what I am saying. The part about the South Pole being only south of one place was a joke.
I did find the idea of going all the way to New Zealand to reach the South Pole from North America a little jarring however and that could be problem in a story if others think the same way.
Try this, then: They’re loaded on a boat in or around Portsmouth, taken down the East Coast and then south to the Panama Canal, through which they pass and then down the West Coast of South America and on to Antarctica. Some transshipping is needed to get them on boats that (a) will not attract attention sailing coastwise along the U.S. coast; (b) will handle a trans-Caribbean cruise; © not attract attention along the Colombia-Peru-Chile coast; and finally (d) will cross the Roaring Sixties to the Antarctic Peninsula.
Getting them from there to the Pole is up to the author’s discretion. My hunch is that in real life you have to have some official reason to be on a flight landing at the Pole, but depending on the scenario for the story, other options could be thrown in. (Why do the kidnappers want to take them to the South Pole, anyway? A secret base there?)
The logic behind going thru the Panama Canal and down the Peru-Chile coast, of course, is that the N.A. East and S.A. West Coasts are in something like a straight line, ceteris paribus, while going down the East Coast of South America would literally take you halfway to Africa.
Possibly, however, as that is the usual way of getting to antarctica, isn’t that a problem with the reader rather than the story?
I just want to note that, whiler travelling by land down from North to South America is possible in priciple, someone I knew tried driving it and foun d that, for political reaasons, he couldn’t drive all the way through. Don’t count on it.
I also knew someone who went to Antarctica by ship. IIRC, their statrt-off point was South America. But then again, they weren’t going to the POle, so the New Zealand route others have suggested might be the best.
Yeah, there’s a great book by Tim Cahill about being on a team of two that set the record for fastest drive from tip of South America to northern tip of Alaska. The mechanical & physical stuff was easy. The challenge was in months of advance work getting together for each border their permissions/visas/licenses to import vehicles/certifications that the vehicle wasn’t being exported illegally/affirmations they weren’t communists/etc/etc.
Keep in mind that Antarctica is a huge continent, almost twice the size of Australia. Where on Antarctica are those characters going? If they are going to the South Pole, that’s hundreds of miles inland (about 800 miles from McMurdo). Are they bringing the necessary transportation and supplies?
By the way, the main reason Americans fly to Antarctica from NZ is because they are heading for McMurdo Station, which is due south of NZ. If you try to get to McMurdo from South America, you’d have to go all the way around Antarctica.
If you’re kidna[pp[ing someone, flying is insane. It doesn’t matter if you’re going to New Zealand, Chile, or anywhere else; it’s just too insecure.
Driving is equally difficult. Driving a kidnapping victim across a free country like the USA, that’s easy. Crossing an international border, not so easy. And boy oh boy, there’s a lot of borders between New Hampshire and Chile, and the further you get from the USA, the more curious the border guards will get. “What are you doing do far from home, sir?”
What you need is a way to avoid security as much as possible.
From New Hampshire your best bet is to drive the victims to one of the major ports, like New York City or Boston, and hop a tramp steamer whose captain will ask no difficult questions.
One in a ship, you needn’t worry about inconvenient border crossings, and practically speaking the transit time won’t be significantly different from driving.
The problems aren’t political, they’re logistical. There is no road across the Darién Gap in eastern Panama and western Colombia. While a few vehicles have been able to make it through, it has required hacking a temporary road out, winching the vehicles through rough parts, and usually rafting across various rivers and swamps. It has taken months, and sometimes years, to get a vehicle across.
The shortest way is of course not necessarily the fastest way. The fastest way is almost certainly via New Zealand. Even if you go via South America, to get to the South Pole you will still need to go in via the Ross Ice shelf, unless you choose an less conventional way. Since this entails going a quarter of the way around Antarctica, any distance savings coming from South America will largely be negated. It is possible to get to the Pole via the Weddell Sea, but that route has rarely been used.
Yep, my parents left on an icebreaker from Buenos Aires to Antarctica.
I can at least say they don’t need to load up too hevily on cash as we operate two ATMs at McMurdo. Man, I’d hate to be the poor sap that has to go down there now and then to re-fill the cash!
Fly 'em to the Patriot Hills with ALE. The DC-6 Michael Palin used in “Pole to Pole” has been replaced with an Ilyushin-76, though.
From the Patriot Hills they can snowmobile it to the Pole. They won’t be allowed into the research station dome, though.
Here’s a helpful link - and the south geomagnetic pole is the location for the Russian Vostok station in Antarctica, but I don’t think a magnetic compass will lead you there.
Re: getting to Antarctica. I’d imagine you’d have trouble moving the kidnapped people in your story to the south pole using someone else’s resources - IIRC, the New York Air National Guard now operates the Antarctic Hercules transports (it used to be the US Navy) and they might not cooperate - so if you fly, you’d want to have your own plane. If you take a ship, again, you’d want it to be your own ship so your nefarious plot is not discovered before you get there.
Once in Antarctica, whoever controls the shelter and mode of transportation doesn’t need to worry about anyone running off for freedom - to do so would be suicide.
Remember, you don’t need to go the whole way around the Earth to get to New Zealand, or at least, not significantly more so than you would going to Chile. That far south, everything’s pretty close together. To go from one point in the far south to another of opposite longitude is significantly less than half the diameter of the Earth.
According to an online distance calculator, it is 8256 kilmetres from New York to Santiago, Chile, and 14420 from New York to Wellington, New Zealand. It’s not half the Earth but it’s a pretty significant difference.
But it’s 7000 km from Santiago to McMurdo Station, and 4000 km from Wellington to McMurdo.
As this map shows, Argentina, Chile, and the Falkland Islands are all closer to both Antartica and the South Pole than New Zealand or Australia are.
So does the map I posted in post #14. As has repeatedly been said, that doesn’t mean anything with regard to whether that’s the best way to get there.
Because that’s where the monsters are 
Once upon a time the protagonist’s father was a scientist, but not a well respected one. He visited the south pole looking for Yeti, but he and his guide got lost in an unexplored area, and found something else entirely. A decade later people who know what he discovered want to recover the creatures, since they’d be valuable. So kidnapping the former scientist and three of his kids for collateral seemed like a good idea to the guys with guns and funds… Hey, it’s a story for kids. Things like this happen in the universes YA fiction inhabit. They occasionally happen in adult fiction too, come to think of it.