When I was at school, they used to call Australia “the antipodes”, I suppose they still do, but antipodean to what? It’s certainly not antipodean to Britain. In fact, if you try this tool you can see that the Aussie mainland is diametrically opposite the open waters of Atlantic Ocean.
So, what about New Zealand? That, as they used to say is “on the other side of the world” too? It was also apparently “antipodean” despite Wellington, NZ being separated from Sydney, Australia, as London is from Moscow and they’re rarely considered to be near neighbours. North Island NZ is actually antipodean to mainland Spain.
So, what place is antipodean to Britain? The South Pacific, it seems, or if you have a boat, the Antipodes a group of islands discovered in 1800 and apparently diametrically opposite Greenwich give or take a bit of rowing.