Covering about 68 hectares (170 acres), it is one of the largest islands on the Rhine in which the river flows unhindered on both sides.

The Rettbergsaue was originally two islands, created through deposition of coarse sediments and flood silts.

Evidence of human settlement dates to the Middle Ages, and probably to Roman times, based on structural remnants found at two sites at the highest elevations of the island.

Because the island is free of traffic and dogs are banned, Rettbergsaue is an especially popular recreation area for families with children.

In the summer, the island is also served by the passenger ferry Tamara, which operates between the beaches and the Schierstein Port and a river landing in Wiesbaden-Biebrich.

The goals of the nature reserve are the preservation and development of the existing island forests, replacement of poplar plantations with native species, and promoting the growth of disease-resistant elms.