A cave or cavern is a natural underground space large enough for a human to enter. Caves form naturally by the weathering of rock and they often extend deep underground. Because of their uniqueness and beauty, some caves around the world have become very interesting places for tourists and photographers worldwide.
Sea Cave in Algarve, Portugal
This beautiful sea cave is located near Benagil Beach in the Algarve region of Portugal. As you can see the bottom of the cave is covered with fine sand, and on the roof there is a “window to the sky”.
Crystal Cave, Iceland
This cave in the glacier ice is the result of glacial mill, or Moulin where rain and melt water on the glacier surface are channeled into streams that enter the glacier at crevices. The waterfall melts a hole into the glacier while the ponded water drains towards lower elevations by forming long ice caves with an outlet at the terminus of the glacier.