The Harle or the Harle Seegatt is a gat in the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

. The Harle runs in a north-south direction between the

East Frisian Islands The East Frisian Islands (German: ''Ostfriesische Inseln'', West Frisian: ''Eastfryske eilannen'', stq, Aastefräiske Ailounds) are a chain of islands in the North Sea, off the coast of East Frisia in Lower Saxony, Germany. The islands extend f ...

of Spiekeroog and

Wangerooge Wangerooge is one of the 32 Frisian Islands in the North Sea located close to the coasts of the Netherlands, Germany and Denmark. It is also a municipality in the district of Friesland in Lower Saxony in Germany. Wangerooge is one of the East F ...

. The main channel subsequently divides into the ''Alte Harle'' (''Muschelbalje'') and the approach to the port of Wangerooge, the ''Dove Harle'' auf. The location and depth of the ''Harle'' navigation channel undergoes major changes. Its depth is published monthly in the

notice to mariners A notice to mariners (NTM or NOTMAR,) advises mariners of important matters affecting navigational safety, including new hydrographic information, changes in channels and aids to navigation, and other important data. Over 60 countries which pr ...

. For a long time

was the island with the greatest movement from west to east. The reason was the ''Harle Seegatt'', which continuously eroded the western tip of the island. The western tip of the island was not protected from erosion until the 1960s, when

groyne A groyne (in the U.S. groin) is a rigid hydraulic structure built perpendicularly from an ocean shore (in coastal engineering) or a river bank, interrupting water flow and limiting the movement of sediment. It is usually made out of wood, concre ...

s and a concrete barrier were built. The longest groyne runs from the western end of Wangerooge to just in front of the eastern tip of Spiekeroog and poses a not insignificant hazard for shipping because it cannot be crossed at

high tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables c ...

. As a result of the expansion of the Wangeroog harbour area,

Niedersachsen Ports Lower Saxony (german: Niedersachsen ; nds, Neddersassen; stq, Läichsaksen) is a German state (') in northwestern Germany. It is the second-largest state by land area, with , and fourth-largest in population (8 million in 2021) among the 16 ...

has become responsible for the transition zone between port and gat. The new channel is known as the Wangeroog Navigation (''Wangerooge Ansteuerung'').N-Ports und Wasser- und Schifffahrtsamt einigen sich auf Grenzen
. Retrieved 22 July 2011

References

External links

Information about the ''Harle'' at www.wattenschipper.de

Diagram with the Harle, Dove Harle and Alte Harle on page 15 of the linked document
(pdf file; 3.93 MB) Wadden Sea Landforms of Lower Saxony Straits of Germany Spiekeroog Wangerooge {{EastFrisia-stub