"Perhaps there was never dictator immortality in the south polar continent."

The lost world is a "polar continent" rather than the interior of a polar island.

The polar continent disappeared beneath the deluge and Hyperborea became invisible again.

When the sea level shrinks enough, the polar continent emerges.

No, I've never been to the polar continent.

That's the south polar continent I'm to be chief administrator of, Master.

Parts of the shell-like polar continent were disappearing beneath this new ocean.

This sighting and similar reports from the 19th century fuelled the belief in a vast polar continent.

Transportation by sea must have been considered; Halvm6rk was mostly ocean, except for the two polar continents and some island chains.

They had built heated domes in the south polar continent.