nz-seafloor-no-land.xml

<Map srs="+proj=merc +lon_0=100 +lat_ts=-41 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs">

  <Style name="color relief style">
    <Rule>
      <RasterSymbolizer mode="normal" />
    </Rule>
  </Style>  
  <Style name="hillshade style">
    <Rule>
      <RasterSymbolizer opacity="0.3" mode="multiply" scaling="bilinear" />
    </Rule>
  </Style>
  <Style name="land style">
    <Rule>
      <PolygonSymbolizer fill="rgb(255,255,255)" />
    </Rule>
  </Style>  

  <Layer name="color relief">
    <StyleName>color relief style</StyleName>
    <Datasource>
      <Parameter name="type">gdal</Parameter>
      <Parameter name="file">nz-bathymetry-relief.tif</Parameter>
    </Datasource>
  </Layer>
  <Layer name="hillshade">
    <StyleName>hillshade style</StyleName>
    <Datasource>
      <Parameter name="type">gdal</Parameter>
      <Parameter name="file">nz-bathymetry-hillslopeshade.tif</Parameter>
    </Datasource>
  </Layer>  
  <Layer name="land" srs="+proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +no_defs">
    <StyleName>land style</StyleName>
    <Datasource>
      <Parameter name="type">shape</Parameter>
      <Parameter name="file">shape/nz-coastlines-and-islands.shp</Parameter>
    </Datasource>
  </Layer> 

</Map>