Bathymetric data requires some spatial processing on QGIS to represent lake bottom elevation contours and lake depth. This tutorial shows the complete procedure to analyse a bathymetric survey on the Lake Patillas in Puerto Rico with QGIS to generate:
Lake bottom DEM
Lake bottom contours
Lake depth DEM
Lake depth contours

Processing data can be downloaded from this link:
https://www.hatarilabs.com/ihen/how...