This is indeed an interesting idea, and I have also read about this possibility. Many years ago, when Admiral Byrd was making his trek to the North Pole, my mother told me that they played the daily communication with Byrd on the radio each day (this was back in the days when reading was the main communication and not television), and as he went further and further north, he started noticing that there was greenery floating in the river that they were following, and that it started getting warmer also. As soon as Byrd started reporting this kind of information, the government immediately stopped transmitting his updates on air, and whatever else he found was never revealed.
In the 1960’s, the book about Hollow Earth came out, and I read about th possibility of the earth actually being hollow. There is a map that shows where the entrances into the earth are located, and there are supposedly several of them in different parts of the world.
If a person looks at the evidence with an open mind, there is a lot of evidence that we do not live on the round globe that we have been taught that we live on, and there is actually a lot of interesting information about the Biblical flat earth as well as a hollow one, and the two are compatible in my opinion.