Calculating Point Nemo

Question

I am referring to Point Nemo which is the point farthest from any emerged land mass. Some relevant information can be found on this page.

I am not sure about -ve signs or whether it is the exact location, but using Google:

pointNemo = GeoPosition[{-48.52, -123.23}] 

GeoGraphics[{pointNemo
  , GeoMarker[{pointNemo}]
  , GeoDisk[pointNemo, Quantity[2700, "Kilometers"]]
  }
 , GeoRange -> Quantity[3500, "Kilometers"]
 , GeoProjection -> "Orthographic"
 ]

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Question(s)

1. Using the Geo* functions in Mathematica, how can the farthest point from any land mass be calculated?

2. What is the closest land mass to Point Nemo?

3. How do I put a label/callout at both these locations?

I am thinking, "why not move this point upwards, since there seems to be plenty of ocean there"?

Answer 1

$Version

(* "14.0.0 for Mac OS X ARM (64-bit) (December 13, 2023)" *)

Clear["Global`*"]

Wolfram does not include all "emerged land" in its data base so its data cannot be used to calculate Point Nemo. See Motu Nui

motunui = GeoPosition[{-27.12, -109.27`}];

pointNemo = GeoPosition[{-48.52, -123.23}];

GeoGraphics[{GeoMarker[{pointNemo, motunui}], 
  GeoDisk[pointNemo, Quantity[2700, "Kilometers"]]},
 GeoRange -> "World",
 GeoProjection -> {"Orthographic", "Centering" -> pointNemo},
 GeoGridLines -> Automatic]