The gigantic Gruta de Benagil sea cave (Benagil Cathedral), Algarve, Portugal

The gigantic Gruta de Benagil sea cave (Benagil Cathedral), Algarve, Portugal

Gruta do Algar do Carvao, cave, Terceira Island, Azores, Portugal, Atlantic, Europe

Monument to Soviet underground partisans, now banished since 1991 to a park near Vilnius, Grutas Park, Lithuania, Europe

Interior of the Gruta do Janelao, a limestone cave passage 100m high, lit through roof window, at Peruacu in Minas Gerais state, Brazil, South America

Cave paintings between 4000 and 5000 years old, Gruta do Janelao, Peruacu, Minas Gerais state, Brazil, South America

Gruta de las Maravillas, lake in a cave, stalactites and stalagmites in a dripstone cave, Aracena, Huelva, Andalusia, Spain, Europe

Gruta de las Maravillas, lake in a cave, stalactites and stalagmites in a dripstone cave, Aracena, Huelva, Andalusia, Spain, Europe

Sculptural Bust Of Lenin In Grutas Park, Also Known As Stalin World, Druskinninkai, Lithuania

Common stingray (Dasyatis pastinaca) inside Gruta azul dive site, eastern coast of Santa Maria Island, Azores, Portugal, Atlantic Ocean