The North Sea, Norwegian Sea, Barents Sea, NE Europe, the Atlantic and the world, each framed once and drawn the same way, so a map of any of them looks like it belongs with the others.
This page needs WebGL 2, which this browser does not provide.
Each map is drawn on your GPU from one 16-bit elevation file. The shelf and coast regions use a shelf depth scale (0 to 1,300 m); the Norwegian Sea, the Atlantic and the world use an ocean scale (0 to 7,000 m) with soft sea-floor shading (the one exception to the no-illumination rule; land stays unshaded) so that ridges, fracture zones and abyssal plains show. The last card is the proof of concept the techniques page is built on.
Each region is built from the best open source for every part of it, finest first and blended with a feathered seam. The example above is one texture averaged to a web-friendly cell; the zoom page shows the finest tiles. Norwegian land is Copernicus GLO-30: Kartverket's lidar terrain service is not open data and is not used.
Sources are open and merged per region by priority, finest first, with a feathered seam. The source plan is a JSON file other tools can read; the long-running build is a resumable script that plans before it fetches. See the research notes.
Land classes (0, 50, 150, 300, 600, 1,000, 1,500, 2,000 m) take one of four ramps by climate zone (Köppen–Geiger, cross-blended over about 6 km). Depth is a continuous gradient on a wider, deeper ramp, so shelves and trenches both read.
Heights are packed into a lossless WebP (height = −11,000 m + 16-bit value × 0.5 m). The shader does the colouring, so the style is a few uniforms. A whole-region texture stays under 8,192 px and about 10 MB, which sets how fine a region example can be.