A cave is a natural underground void large enough for a human to enter.

Cave

A cave is a natural underground void large enough for a human to enter.

An illustration of a cliff with with a cave. A cave is a natural underground void large enough for a human to enter.

Cave

An illustration of a cliff with with a cave. A cave is a natural underground void large enough for a…

A Reindeer age masterpiece painting in four colours of a buffalo. Painted in the Cave of Altamira in Spain.

Reindeer Age Cave painting

A Reindeer age masterpiece painting in four colours of a buffalo. Painted in the Cave of Altamira in…

A cartoon drawing of soldiers entering a dark cave where a giant resides.

In Doubting Castle

A cartoon drawing of soldiers entering a dark cave where a giant resides.

An example of a typical cave dwelling from the Stone Age.

Cave Dwelling

An example of a typical cave dwelling from the Stone Age.

Reindeer Age (Aurignacian) Engravings and Carvings. Shown are engravings of stage and salmon, engraved on reindeer horn, engraved stone, head of a women carved in ivory, horses head carved in ivory, stone statuettes, and painted pebbles (Azilian age).

Reindeer Age Engravings and Carvings

Reindeer Age (Aurignacian) Engravings and Carvings. Shown are engravings of stage and salmon, engraved…

The Samphire gatherer, "there are few avocations attended with so much danger, as that of gathering rock samphire, which grows in great plenty along the edges and down the perpendicular sides of the cliffs near Rennel's cave, in Glamorganshire, Wales."

The Samphire Gatherer

The Samphire gatherer, "there are few avocations attended with so much danger, as that of gathering…

An illustration of a giant sitting in a cave playing with a herd of sheep.

Giant Sitting in Cave with Sheep

An illustration of a giant sitting in a cave playing with a herd of sheep.

In Norse mythology, Baldur is killed by an arrow wrapped with mistletoe (Baldur's only weakness), which is shot by his blind brother Hodur. Hodur is tricked into doing so by Loki. When Baldur is sent to the Spirit World, Hela says she will give him back if everyone weeps for him. Loki dressed as an old woman refuses to weep so Baldur is lost to the Sprit World.

Loki as an Old Woman

In Norse mythology, Baldur is killed by an arrow wrapped with mistletoe (Baldur's only weakness), which…

The entrance to Mammoth Cave, Kentucky.

Mammoth Cave

The entrance to Mammoth Cave, Kentucky.

An illustration of a man hiding in a cave which a storm churns outside.

Man in Cave

An illustration of a man hiding in a cave which a storm churns outside.

"Cave's modification of Nasmyth's Hammer." — The Encyclopedia Britannica, 1893

Nasmyth's Hammer

"Cave's modification of Nasmyth's Hammer." — The Encyclopedia Britannica, 1893

Natural Bridge in Rockbridge County, Virginia is a geological formation in which Cedar Creek has carved a gorge of the limestone forming an arch 215 ft high with a span of 90 ft.

The Natural Bridge in Virginia

Natural Bridge in Rockbridge County, Virginia is a geological formation in which Cedar Creek has carved…

Pirates of the eighteenth century at their cave.

Pirates

Pirates of the eighteenth century at their cave.

Sigmund and his wife Sieglinde are traveling with their son, Siegfried. They are attacked by robbers. The dwarf Regin helps Sieglinde and eventually raises Siegfried as his own.

Regin Helping Sieglinde and Siegfried

Sigmund and his wife Sieglinde are traveling with their son, Siegfried. They are attacked by robbers.…

This sign indicates that spelunking is located nearby.

Spelunking, Black and White

This sign indicates that spelunking is located nearby.

This sign indicates that spelunking is located nearby.

Spelunking, Color

This sign indicates that spelunking is located nearby.

This sign indicates that spelunking is located nearby.

Spelunking, Outline

This sign indicates that spelunking is located nearby.

This sign indicates that spelunking is located nearby.

Spelunking, Silhouette

This sign indicates that spelunking is located nearby.