Errors in the bathymetry raster ?

[cyrilrader]

Hello,

I was making QC on datasets using the EMODnetBiocheck tool (https://github.com/EMODnet/EMODnetBiocheck) and I've noticed something weird. The QC tool detected that the depth value is greater than the value found in the bathymetry raster and the value from the bathymetry is negative. Here is a picture of this:

First, I thought that it was because some occurrences were situated on land but in fact it wasn't the case. So, I investigated further by searching how the QC tool was making the check on depths. I've noticed that it's using the 'check_depth' function from the obistool package. When looking at the documentation of this function, I've noticed that if you don't provide a raster, the default one from xylookup service will be used. So, I decided to use 'lookup_xy' on the dataset to see more in details what's in the raster. I find the results weird but maybe there is something that I don't understand correctly. Here a picture of the results:

What I don't understand is that no matter if the 'shoredistance' is positive or negative, there are negative bathymetry values. Is there a problem with the raster and it has negative depth value for point located in the sea? Or did I misunderstand something?

Thanks in advance for your time and help!