Warning: Looking at these photos will definitely make you start feeling a little claustrophobic.
Peak District, England
Source: Earthwatcher / via: earthwatcher
Qassiarsuk – Erik the Red's former farm in Greenland
Source: Clare Rowland/Creative Commons / via: clurr
Benbulbin in the Dartry Mountains in Ireland
Source: Gerard Levitt/Creative Commons / via: copperkettle
Ellidaey Island, Iceland
Source: Chris Zielecki/Creative Commons / via: zanthia
