The basin ID gives the answer without any tracing. To see the path itself, switch to the example basin above the map and click a pixel: the page follows the flow directions step by step until the water reaches the outlet.
Basin details
Follow the water from any pixel to the outlet
The basin mask says which basin a pixel belongs to. The flow-direction raster says which of a pixel’s eight neighbours the water moves to next. Click anywhere inside the basin on the map: the page steps from neighbour to neighbour until the water stops moving, and every starting point ends at the same pixel — the outlet of basin 8595. This runs entirely in your browser, on the flow directions for this one basin.
Flow path from the clicked pixel
traced flow path
outlet of basin 8595