To smooth contour lines, select the Contours layer in the Contents window. In the Properties window, on the General page, set the Smoothing value.

In some cases smoothing contours via the contour properties can cause some contours to touch or cross. In these cases, you cannot use the contour layer properties to smooth the contour lines. You can instead smooth the grid file. To do this, you have the following options:

• Right click on the Contours layer in the Contents window and click Edit Grid, then use the Grid Editor | Tools commands to edit the grid.
• Grid the data with twice as many grid nodes for a smoother result (increase the # of Nodes in the Grid Data or Grid Mosaic dialog). 
• Smooth the grid file using Grids | Edit | Spline Smooth.
• Smooth the grid file using Grids | Edit | Filter, and choosing a low-pass filter.

Once you have a new grid file, substitute the new grid file in the contour layer, or create a new contour map from the new grid file.

Updated November 22, 2021