The last link in this sentence needs to be updated, because it doesn't resolve to a specific heading:
You can use the Marine Regions gazetteer to search for your region of interest and obtain midpoint coordinates. Guidelines for using this tool and for dealing with uncertain geolocations can be found here.
In this section: https://manual.obis.org/common_formatissues.html#missing-required-fields
The last link in this sentence needs to be updated, because it doesn't resolve to a specific heading:
I think it's intended to link to this section: https://manual.obis.org/common_qc.html#uncertain-geolocation