Why Mariannenaue stands out
Mariannenaue is best known as a protected Rhine island in the Rheingau, distinguished by its Auenwald floodplain forests with veteran trees up to four centuries old, its importance for breeding and migratory waterbirds, and its cultivated vineyards of Schloss Reinhartshausen that occupy almost the entire island surface.
Mariannenaue history and protected-area timeline
Mariannenaue originally existed as two separate islands, both formed roughly 10,000 years ago from calcareous sediments carried down from the Alps by the Rhine. The islands merged naturally in the 18th century through ongoing sedimentation, and the faint boundary depression, still lined with floodplain forest, is visible across the surface today.
The eastern, smaller parcel had belonged from early times to the knightly estate that later became Schloss Reinhartshausen. The much larger western parcel, known as the Hattenheimer Aue, had been held by the Langwerth von Simmern family since 1464 and was historically administered under the Ingelheim knightly court before being reassigned, after long legal disputes, to the Rheingau in the 18th century. Some local historians have suggested that this same island is the place where Emperor Louis the Pious died in the year 840, opposite Ingelheim.
In 1800 Count Clemens August von Westphalen acquired both island portions together with Schloss Reinhartshausen. He unified them under the name Westfälische Aue and laid out a landscape park aligned with the schloss. In 1902 the island was renamed Mariannenaue in honor of Princess Marianne of Orange-Nassau, who had owned the schloss from 1855 and lived there until her death in 1883.
Mariannenaue landscape and geographic character
Mariannenaue is a low, elongated river island that hugs the right bank of the Upper Rhine for several kilometers between Erbach and Hattenheim. Its surface is essentially flat, built from calcareous alluvium deposited by the Rhine over millennia, and its widest point reaches about 300 meters. A long depression runs diagonally across the island, marking where two former islands merged and where floodplain forest still grows.
The island is framed by active river flow on one side and still-water channels on the other. The Große Gieß to the south and the Kleine Gieß to the north create sheltered, near-static waters that widen the effective ecological footprint well beyond the dry land of the island itself. Long training groynes extending downstream from Eltville to Oestrich-Winkel shape the riverbed around the island and reinforce this contrast between moving and calm water that defines the local landscape character.
Mariannenaue ecosystems, habitats, and plant life
The ecological character of Mariannenaue is shaped by the coexistence of floodplain forest, riverbank habitat, and the still waters of the surrounding Gießen. The Auenwald contains very old trees, with some individuals estimated at up to four hundred years, making the forest one of the more notable veteran-tree habitats along this stretch of the Rhine.
The combination of sheltered waters, wooded banks, and exposed gravel areas provides nesting and feeding conditions for a range of bird species, and the island functions both as a breeding ground and as a resting and overwintering area for migratory birds. Mammals recorded on the island include a rare beaver species. Roe deer and wild boar regularly cross the river to and from the island, with the result that population dynamics on land and on the island cannot be considered in isolation.
Mariannenaue wildlife and species highlights
Mariannenaue supports a distinctive island river fauna shaped by its mix of forest, still water, and exposed riverbank. The island is recorded as a breeding area for cormorants, grey herons, and black kites, and it functions as a resting and overwintering site for numerous migratory bird species moving along the Rhine corridor. A rare beaver species is documented as resident on the island.
On the larger mammal side, roe deer and wild boar are actively hunted here, and the river itself acts as a regular crossing route; animals swim from the mainland on either side to reach the island and back, so the population is not isolated. This openness is also ecologically consequential: in late 2024 cases of African swine fever were confirmed in wild boar on the island and on the adjacent right-bank mainland between Erbach and Hattenheim, illustrating how tightly the island's wildlife dynamics are tied to those of the surrounding Rheingau land.
Mariannenaue conservation status and protection priorities
The island and its surrounding groynes and still water zones have been a designated nature reserve (Naturschutzgebiet) since November 1972. Since 1974 it has been recognized as a European nature reserve and a Fauna-Flora-Habitat (FFH) area under the EU Habitats Directive, giving it formal transboundary ecological status that connects it to broader European habitat networks along the Upper Rhine.
Mariannenaue cultural meaning and human context
The island has long been embedded in the wine-growing and noble estate culture of the Rheingau. Schloss Reinhartshausen on the right bank acquired and unified the two former island parts in 1800, creating a landscape park oriented toward the schloss, and the island was subsequently renamed after Princess Marianne of Orange-Nassau, who made the schloss her residence from 1855 until 1883. The vineyards today are part of the historic Rheingau wine tradition, with named sites including Erbacher Rheinhell and Hattenheimer Rheingarten.
Top sights and standout views in Mariannenaue
Highlights of Mariannenaue include its setting as one of the larger Rhine islands in the Upper Rhine valley, the old Auenwald forests running diagonally across the island where two former islands once merged, the protected still waters of the Kleine Gieß and Große Gieß on either side, the bird breeding and resting colonies along the river, and the unusual agricultural character of a wine estate that has operated continuously on a river island for centuries.
Best time to visit Mariannenaue
Spring and early summer bring the most vivid vegetation and active birdlife, while autumn is the period of grape harvest on the island. The surrounding flowing river water moderates temperatures through the year, so summer heat is softened, but visitors should note that access is only possible as part of guided tours and that the still waters around the island are seasonally closed to boats, generally between autumn and early spring.
