What are the mudflats?
The mudflats (Watt) are the sea floor along the coast that, according to the Wadden Sea National Park, falls dry twice a day and is flooded again. With every tide, material is washed away in one place and deposited in another, so the flats look a little different every day.
Depending on how calm the water is, different grounds form. In calm, sheltered areas fine particles settle and form soft, often dark mud flats. Where the water moves more, coarser grains stay behind: mixed and sand flats are firm and easy to walk on.
Tidal creeks: the waterways of the flats
Tidal creeks (Priele) are channels that run through the mudflats up into the salt marshes. At ebb the water drains through them towards the North Sea; at flood it flows back in. Because creeks carry water even at low tide, shrimp and fish wait in them for the next flood.
For walkers, tidal creeks are the biggest trap. The national park warns: they often look like small trickles, but with the flood they fill into fast-flowing water that can no longer be crossed on the way back. So never cross tidal creeks, and never walk far out onto the flats without a mudflat guide.
Who lives on the mudflats
At first glance the mudflats look empty, but the ground is full of life. According to the national park, one square metre of mudflat holds millions of diatoms, thousands of tiny crustaceans and many mussels, snails and worms. Altogether the Wadden Sea is home to around 10,000 animal and plant species.
The national park calls five typical residents the “Small Five”: the lugworm, which eats sand and leaves the familiar coiled casts; the common cockle, the most common shell in the Wadden Sea; the shore crab, which takes cover from gulls at low tide; the mud snail, of which up to 200,000 can live on one square metre; and the brown shrimp, known in Germany as the “Krabbe” in a shrimp roll.
Countless birds live off this food supply: over a year up to 10 million birds rest in the Wadden Sea, and during the main migration in spring and autumn around 6 million at the same time. Harbour seals and grey seals lie on the sandbanks; keep a safe distance from them.
World Heritage Site and national park
The German, Danish and Dutch Wadden Sea has been a UNESCO World Heritage Site since 2009. The German part is protected as a national park. For your visit this means: stay on the paths, don’t disturb the animals and follow the rules on site.
Before you go onto the mudflats, check on the tide map when high and low tide are at your place, and join a guided mudflat walk for longer tours.
Twice a day the mudflats are sea floor and twice a day sea. Enjoy them near the beach, never cross tidal creeks and only go further out with a guide.
See the tide for your placeFrequently asked questions
How often do the mudflats fall dry?
Twice a day. Two high tides are on average 12 hours and 25 minutes apart, so the time shifts every day.
What are the little piles on the mudflats?
They are the casts of the lugworm. It eats sand, digests the tiny food particles in it and leaves the cleaned sand behind as coiled piles.
Can I go onto the mudflats on my own?
Near the beach yes, keeping an eye on the tide. According to the national park, you should only go far out with a mudflat guide and never cross tidal creeks.