I remember reading this ca. 1974. It was a YA novel in English that I got from my school library. They had a mass-market paperback copy. Unfortunately my memory is extremely sketchy, since it was a long time ago, and I was a little kid.

I remember two main things in the book that excited my imagination:

  • There are lizard-like intelligent bipeds.

  • There are machines sort of like underground submarines, or Mole Man's vehicle in the Marvel universe. They burrow deep underground, I think all the way down into the Earth's mantle. I think a lot of the plot involves people chasing each other underground in these vehicles, or racing against time.

  • 1
    Did the underground people build with diamond? Aug 30, 2020 at 8:18
  • @AntonSherwood: I don't remember that, but my memory is very faded after 45 years :-) I actually don't remember if the lizard people lived underground, although that would make sense.
    – user2490
    Aug 30, 2020 at 23:21
  • @AntonSherwood I was going to suggest the same book, but have blanked out on the title.
    – NJohnny
    Sep 2, 2020 at 15:24

2 Answers 2


Maybe Stranger from the Depths (1967) by Gerry Turner.

Book cover showing a green humanoid with webbed hands and bulging eyes swimming in psychedelic looking water

The lizard people lived in underground cities.

They traveled between their cities with an underground vehicle. (I can't remember if it was like a subway or a digging machine)

They used synthetic diamonds in much of their construction, for example the dome over the city, and a small (one foot?) statue of a lizard man.

The story begins with a group of teens/young adults finding a diamond lizard statue after an earthquake. Later, exploring the area, they wake up a lizard man from stasis pod. He had been in there a VERY long time. He leads them to his city, but it's deserted so they travel to another city trying to find answers.

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    That's it, instantly recognized the cover -- thanks! I'll award the bounty when the UI lets me. Wow, copies are not to be had at any reasonable price. Obviously many others liked this book as kids.
    – user2490
    Sep 2, 2020 at 20:48

Could it be At the Earth's Core (1914) by Edgar Rice Burroughs?

I have not read it, but in Wikipedia's description, a miner named David Innes has an experimental excavating vehicle called an "iron mole".

There is a problem with the vehicle and they end up burrowing 500 miles into the Earth's crust and discover a land underneath -- a kind of hollow Earth -- called Pellucidar.

It has several different kinds of creatures, including the Mahars, which are intelligent flying reptiles.

  • Thanks, but this is not the book I had in mind.
    – user2490
    Sep 2, 2020 at 20:52
  • I have read both (many years apart!). In the Burroughs, there is no “earth's mantle”. Sep 3, 2020 at 6:56
  • @AntonSherwood call it what you like, but 500 miles in passes the crust and enters the mantle :-) So even if the earth has a hollow area for Pellucidar, some part of the mantle is there. But I can't argue with the fact that the OP says it's a different book....
    – Basya
    Sep 3, 2020 at 10:46