Extinct volcano (actually, only the eastern half of it is left above water).
It is only fitting that as model #400 I would put up the place where I did my first geological mapping course as a student.
* Generator: [DEM Net Elevation API](https://elevationapi.com)
* Digital Elevation Model: [AW3D30 OpenTopography](https://opentopography.org/)
* Imagery: [Esri World Imagery](https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer)