There are events without elevation gain such as motorboat races, open water swimming, or even city marathons. You can now use the elevation diagram as a line showing the progress without ups and downs. The 1D-feature makes competitions with laps more understandable for spectators.
Swimming contest with 1D line and with "normal" elevation chart below.
You set up the elevation chart in the tracking map section of your basic tab. Set min and max value of elevation "0".