As a newcomer to using GIS for research, I am wondering if there are online repositories for spatial data, similar to package repositories for Linux distributions.
For instance, I would be able to find things like "bathymetric map of the world's oceans", or "administrative regions map for the United States", etc.
Is there such a repository/website where I can download such data? Or do I have to "start from scratch" and manually draw a map of the world if I need one?
I prefer QGIS and other open source GIS software for the above.