Average distance the to nearest ice-free coast (1000 km). To calculate the average distance to the closest ice-free coast in each country, Nunn and Puga first compute the distance to the nearest ice-free coast for every point in the country in equi-rectangular projection with standard parallels at 30 degrees, on the basis of sea and sea ice area features contained in the fifth edition of the Digital Chart of the World (US National Imagery and Mapping Agency, 2000) and the country boundaries described above. Then Nunn and Puga average this distance across all land in each country not covered by inland water features. Units are thousands of kilometres.