We present a new dataset and algorithm for fast and efficient coastal distance calculations from any point on Earth. Previous global coastal distance datasets have been generated at relatively coarse resolution (e.g., 4 km), limiting their utility in many real-world contexts. Publicly available satellite imagery combined with computer vision enable much higher precision. We provide a global coastline dataset at 10 meter resolution, a 400-fold improvement over existing data. To handle the computational challenge of querying at such an increased scale, we introduce Lighthouse (Layered Iterative Geospatial Hierarchical Terrain-Oriented Unified Search Engine). Our method is both extremely fast and efficient, making it well-suited for real-time inference in resource-constrained environments.