The Site consists of former tidal channels and creeks, mud flats, salt marshes and higher ground with young shifting dunes. The former Ramsar Site Oosterschelde & Markiezaat has been designated as two separate Sites Markiezaat and Oosterschelde (which retains Site no. 354), following Natura 2000 boundaries. The Sites are not connected and their ecology is very different. The adjustment of the Markiezaat Site boundary has resulted in an increase of 10 ha. It is an internationally important area for European threatened breeding birds such as Eurasian spoonbill, avocet and Kentish plover. Moreover, the Site regularly supports more than 20,000 wintering birds and more than 1% of the individuals of the populations of five species of waterbirds. Land use is dedicated to dairy farming, forestry and outdoor recreation activities. The Site includes a visitor centre, hiking trails and observation hides. The main threats are posed by agriculture intensification, industrialization, urbanization, waste water discharge and construction of infrastructure such as power lines.