I have a baselayer (.shp file), with bathymetric contours. I want to measure the distance from each grid square in a grid, to the nearest nominated depth (so was hoping to have a way to also nomate specifically to -120 m in the .shp file).
I generally have a basic understanding of the functions of QGIS, but have absolutely no idea where to start.
I'm using QGIS v3.2.1
I have tried the below answer from Kazuhito, but appear to be getting scores that are UTM figures. I've attached photos of where I am at now.