The Site is formed by a part of Lake Velence, the second biggest lake in the country, and Dinnyési-fertő, a marshland. The Lake features floating marshes which are among its most important habitats: they provide good conditions for plant species such as the orchid Liparis loeselii and Sphagnum mosses, as well as for animal species including the weatherfish Misgurnus fossilis, which has a stable population in the area. The Site is an important breeding, wintering and staging area for numerous species of endangered waterbirds, such as the moustached warbler Acrocephalus melanopogon. It regularly supports an average of 60,000 to 70,000 waterfowl per year, and more than 1% of the individuals of the population of greater white-fronted goose Anser albifrons and greylag goose Anser anser. The wetland area plays an important role in water purification, flood control and climate regulation, and provides several cultural services. Human activities include reed harvesting on the lake, grazing and mowing of the meadows in Dinnyés. There are several birdwatching towers and a research facility at the Site. Recreational and tourism activities, dams and water management, and illegal fishing pose threats to the Site.