Wetland · Hong Kong
Mai Po Marshes
米埔
Mangroves, mudflats and shrimp ponds on Deep Bay, a crossroads of the East Asian flyway
The Mai Po Marshes in the north-western New Territories are a mosaic of mangroves, intertidal mudflats, reed beds and traditional gei wai shrimp ponds on the shore of Deep Bay, facing Shenzhen. A key stop for migratory waterbirds on the East Asian–Australasian Flyway, they were listed with Inner Deep Bay as a Ramsar site in 1995, and access is managed through permits and guided visits.
- Ramsar site (Mai Po and Inner Deep Bay) · 1995
- Restricted area under Hong Kong wildlife law
Key facts
Overview
Mai Po lies at the mouth of the Shenzhen river, where the fresh water of the river meets the brackish tides of Deep Bay (后海湾, Hòuhǎi Wān; Shenzhen Bay on the mainland side). Its mangroves are among the largest in Hong Kong, and the mudflats beyond them, exposed at low tide, feed tens of thousands of shorebirds on migration and in winter. Behind the mangroves lie the gei wai, shallow tidal ponds once used to farm shrimp and now managed for wildlife.
The core of the marshes is the Mai Po Nature Reserve, managed by WWF-Hong Kong under the Agriculture, Fisheries and Conservation Department, while the wider Ramsar site includes the fishponds and mudflats of Inner Deep Bay. Across the bay, the Futian mangroves of Shenzhen protect the other shore, and the two cities' skylines frame the wetland.
How the landscape formed
Deep Bay is a shallow estuarine embayment of the Pearl River Delta, filling with fine sediment brought by the Shenzhen river and the delta's currents. The mudflats grow outwards as sediment accumulates, and mangroves colonise their landward edge, trapping more mud. Over the twentieth century, people dug gei wai and fishponds in the reclaimed land behind the mangroves, creating the mixture of natural and managed wetlands that makes Mai Po so rich for birds.
Highlights
Gei wai
基围
Traditional intertidal shrimp ponds fringed with mangroves, filled and drained by tidal sluices; Mai Po's are among the last in the Pearl River Delta. Cantonese: gei wai.
Floating boardwalk hides
浮桥观鸟屋
Hides at the end of a boardwalk through the mangroves to the edge of the mudflats, where birds come close on the rising tide.
Deep Bay
后海湾
The shallow bay shared by Hong Kong and Shenzhen, whose tidal mudflats are the feeding grounds for the birds. Cantonese: Hau Hoi Wan.
Hong Kong Wetland Park
香港湿地公园
A public wetland park at Tin Shui Wai nearby, with a visitor centre, open for everyone to learn about the Deep Bay wetlands.
Plants and wildlife
Mai Po is one of the most important wetlands on the East Asian–Australasian Flyway, the migration route that links Siberia and Alaska with South-east Asia and Australia. In winter and on passage it hosts large numbers of ducks, herons, egrets and shorebirds, including a substantial share of the world's black-faced spoonbills. The site is also a centre of training in wetland management for the region.
Plants
Kandelia
秋茄
Kandelia obovata, the most common mangrove at Mai Po.
Reed beds
芦苇
Common reed along the fresher margins, habitat for warblers and wintering buntings.
Holly mangrove
老鼠簕
Acanthus ilicifolius, a spiny shrub of the mangrove fringe.
Wildlife
Black-faced spoonbill
黑脸琵鹭
An endangered wader of East Asia; Deep Bay is one of its most important wintering sites.
Spoon-billed sandpiper
勺嘴鹬
A critically endangered sandpiper occasionally recorded on passage on the mudflats.
Saunders's gull
黑嘴鸥
A threatened gull that winters on the bay.
Eurasian otter
欧亚水獭
Rare in Hong Kong, surviving in the Deep Bay wetlands.
Culture and legend
The gei wai were part of a traditional way of life in the Deep Bay villages, where families farmed shrimp and fish in tidal ponds. The Mai Po gei wai ceased commercial operation, but are now managed by traditional methods to keep the habitat alive. The area is close to the boundary with Shenzhen, which has long limited development and helped the wetlands survive.
Frontier closed area
边境禁区
The former border restricted zone along the Shenzhen river, which kept the marshes largely free of development. Cantonese: bin ging gam keui.
Mai Po
米埔
The Cantonese name of the area and its village. Cantonese (Jyutping): mai5 bou3.
History
1940s–1970s
Gei wai and fishponds dug
Villagers convert land behind the mangroves into tidal shrimp ponds and fishponds.
1983
WWF-Hong Kong takes on management
The Mai Po Nature Reserve begins to be managed for conservation and education.
1995
Ramsar site
Mai Po and Inner Deep Bay are listed as a wetland of international importance.
2006
Hong Kong Wetland Park opens
A public park and visitor centre at Tin Shui Wai presents the Deep Bay wetlands to a wider audience.
Through the seasons
Spring
Northward migration peaks from March to May, with shorebirds in breeding plumage on the mudflats.
Summer
Hot and wet; fewer birds, but breeding egrets and herons and active mangrove life.
Autumn
Southward migration from September, with waders and the arrival of the first ducks and spoonbills.
Winter
The peak of the birdwatching season, with large flocks of ducks and the wintering black-faced spoonbills.
Routes and ways in
Guided reserve visit
The usual way in for the public: a guided walk through the reserve's gei wai, ponds and hides, organised by the reserve managers.
Boardwalk to the mudflat hides
For permit holders and guided groups, the boardwalk through the mangroves leads to hides on the edge of Deep Bay, best on a rising tide.
Practical notes
- Mai Po is a restricted area: entry requires a permit from the Agriculture, Fisheries and Conservation Department or a place on an organised guided visit. The Hong Kong Wetland Park nearby is open to the public.
- Birdwatching depends on the tides; visits timed to high tide in Deep Bay bring birds closer to the hides.
- Binoculars and a telescope are essential; wear muted clothing and keep quiet in the hides.
- Mai Po lies in Yuen Long district near the Lok Ma Chau boundary with Shenzhen.
Frequently asked questions
Sources
- Ramsar Sites Information Service — Ramsar Convention Secretariat (retrieved 27 September 2026)
- Mai Po Inner Deep Bay Ramsar Site — Agriculture, Fisheries and Conservation Department, HKSAR Government (retrieved 27 September 2026)
- Mai Po Nature Reserve — WWF-Hong Kong (retrieved 27 September 2026)
- Hong Kong Wetland Park — Agriculture, Fisheries and Conservation Department, HKSAR Government (retrieved 27 September 2026)
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