Natural Earth 10m coastline is too coarse for 30 m Landsat kelp pixels

When drawing nearshore Landsat pixels (30 m) over Natural Earth's 10 m land polygons, 12-16% of kelp-habitat pixels in two California stretches (Sonoma-Mendocino, Monterey-Big Sur) fell inside the land polygons, while one dense 8 km window had none. So the error varies along the coast and is several pixels wide. It's fine for coast-scale maps with aggregated cells, but not for close-ups drawn to true scale; use a finer shoreline such as CDIP MOP points (100 m spacing) for the California mainland. Check it with shapely's union_all().contains(points(lon, lat)) on the pixel centres before choosing a basemap. A whole 150 km stretch drawn to scale also collapses into a line a few screen pixels wide, so pair a close-up drawn to scale with an unrolled along-shore view.