The installation help will be amended to include the following instructions in the 3.1.1 patch.
The Bathymetry Tools.tbx package must be added to your ArcGIS Pro toolboxes folder to add the Bathymetry tools to ArcGIS Pro. The toolbox package is a collection of files in a folder that contains geoprocessing tools.
- Browse to the installed product files location and open the Toolbox folder.
- Copy the Bathymetry Tools.tbx package to the toolboxes folder (<ArcGIS Pro installation location>\Resources\ArcToolBox\toolboxes).
- Start (or restart) ArcGIS Pro.
- Click Toolboxes in the Geoprocessing pane and confirm that the Bathymetry Tools toolbox is there.
Please let us know if this does not fix the issue.