I can get the postion with this code

    pos = First[
      Flatten[#, 1] & /@ 
       First[Entity[
          "AdministrativeDivision", {"California", "UnitedStates"}][
         EntityProperty["AdministrativeDivision", "Polygon"]]]]
You can see the postion in the map

    GeoListPlot[GeoPosition[pos]]
![Mathematica graphics](http://i.stack.imgur.com/G7gVe.png)

I can get their elevation

    eleData = 
     QuantityMagnitude[
      GeoElevationData[
       Flatten[#, 1] & /@ 
        First[Entity[
           "AdministrativeDivision", {"California", "UnitedStates"}][
          EntityProperty["AdministrativeDivision", "Polygon"]]]]]

Then I get the data

    data = Flatten /@ Transpose[{pos, List /@ eleData}]
I can plot its discrete plot

    ListPointPlot3D[data]
![Mathematica graphics](http://i.stack.imgur.com/PNgQT.png)

But how to connected those discrete points to get a **smooth boundary**?