Looking at different world maps, I noticed that there is considerable variety in how the coastline of Antarctica is depicted (even when taking the different map projections into consideration).
Are these discrepancies caused by the fact that the coastline of Antarctica has not been precisely mapped because the ice sheet obscures it in satellite and aerial photography? Do we have the technology to look through the ice sheet and locate the bedrock and has it been used on every part of Antarctica's coastline, or does map data still contain some guess work and interpolation?
Or are there perhaps competing ideas about how a coastline covered in ice should be outlined on a map? I noticed e.g. that Google Maps displays Berkner Island while Wikipedia claims that the island's bedrock is completely below sea-level.
Examples: Google Maps has a very different outline for the islands under the Filchner-Ronne ice shelf than other sources:
example 1: from Google Maps
example 2: from an example using the D3-Geo-Projection code library (not sure where the dataset is from)
example 3: from Wikipedia's Antarctica article (similar to example 2, but using a very different projection)