<terrainshader>
      <code>
        <![CDATA[
          #pragma vp_entryPoint disableBathymetry
          #pragma vp_location vertex_view

          float oe_terrain_getElevation(in vec2); // osgEarth SDK
          vec4 oe_layer_tilec;                    // global tile coords
          vec3 oe_UpVectorView;                   // up vector

          void disableBathymetry(inout vec4 vert)
          {
            float elev = oe_terrain_getElevation(oe_layer_tilec.st);
            if ( elev < 0.0 )
            {
                vert.xyz -= oe_UpVectorView*elev;
            }
          }
        ]]>
      </code>
    </terrainshader>