Historic: exploring and using underground spaces

The structure of the Earth: the core, the mantle, the earth's crust

Notable achievements: salt mining, the exploitation of "black gold" (oil), the emergence of marine drilling, natural gas, geothermal energy, drilling for thermal waters, the discovery of deposits of various useful minerals, drinking water under the Sahara desert

Portrait gallery: Emil Racoviță, Constantin Beca

Exemplary stories: Cave of Giant Crystals in Naica

Exploration through Imaginary/Speculative Fiction: A journey to the center of the Earth

Weird assumptions: the article series The wall of silence, Passport to Magonia: From Folklore to Flying Saucers,

glass planet: non-biological hypercivilization, the quartz crystal

conspiracy: Hollow Earth Theory, Edmund Halley, Richard E. Byrd

Communities of Explorers: ASFAN-Romania, STRING Center, ARES Alliance, ICER

UFOlogical Archive from Romania: the establishment of the ufological library