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Norfolk’s Great Barrier Reef

When you walk the marshes, the coastal path or just gaze out to sea, take a moment to marvel in the knowledge that just off the shingle shore at Cley and running eastwards along the coast to Cromer and beyond lies Europe’s - and possibly the world’s - largest chalk reef.

Dubbed Norfolk’s Great Barrier Reef, it lies just a few metres below the sea’s surface. It is a maze of boulders, stacks and arches running 32 km (20 miles) from Cley to Cromer and further east to Trimingham.

Most reefs in the UK are made up of hard rock. Few are chalk. This reef is millions of years old made up from vast numbers of ancient plankton which formed a layer up to 460m thick.

The full extent of this rare habitat was only discovered some eight years ago when local divers mapped its length and size.

The reef’s chalk beds teem with marine life including purple sea slugs and orange anemones. It attracts creatures such as shrimps and prawns, marine worms and tiny snails which in turn provide food for fish and foraging seabirds.

It is home to blue mussel beds, over 30 species of sea slug, harbour porpoises, and grey and harbour seals, alongside occasional sightings of sunfish and basking sharks.

The beach at Cromer is seen as the gateway to the reef known as the Cromer Shoal Chalk Beds. The beds - just 200 metres off the coast - extend out into the sea with amazing white-walled arch formations surrounded by a seabed of rocks, peat and clay. They cover an area of around 320sq km and extend some 10km into the North Sea.

At certain places, such as West Runton, exposed chalk can be clearly seen during low tide, hinting at the wider chalk treasure lying a little further offshore.

In 2008, divers discovered a species of purple sponge entirely new to science.

A diver with aqualung swims within the shapes of the chalk reef
A diver swims among the chalk landscape which make up Norfolk's Great Barrier Reef

The more sheltered chalk beds towards Cley and Blakeney are home to swathes of lush seagrass which provides safe haven for juvenile and adult fish, shellfish and invertebrates. This rich variety of marine life acts as a huge larder for diving seabirds, such as the little, sandwich and common tern which nest in shallow scrapes along the sandy beaches.

Seagrass beds are rare and a vulnerable habitat. On the Norfolk coast they form part of an internationally important coastal eco-system which stablises fine sediment and improves water quality.

Seagrass beds make a contribution to managing climate change. Each square kilometre stores ten times as much carbon as a temperate forest.

The reef is one-and-a-half times longer than the 14 mile-long Thanet coast chalk reef in Kent, previously the longest in the world. Britain has three quarters of all Europe’s chalk reefs.

In January 2016, the reef was designated as a Marine Conservation Zone (MCZ). The MCZ means that sea life such as the threatened pink sea fan coral, which grows on the reef, will now be protected, along with hundreds of species including crabs and lobsters that colonise the soft chalk beds.

Divers Dawn Watson and Rob Spray have created a fascinating underwater video of the reef for the Wildlife Trusts. You can see it here:

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