UKD Seahorse

is a UK Dredger vessel based in Southampton and up here (Port King's Lynn) for a while to dredge the river bed at the entrance to the Alexandra Dock. The river is tidal here and the river bed is sandy mud and its contours vary over time so it becomes necessary  to remove the mounds so that the large cargo vessels that visit here can enter and leave, manoeuvres done around high tide, without scraping the river floor.

The extra shows a typical cargo vessel at King's Lynn. Peruse the map in satellite view if you wish to appreciate the locality.

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