RICHARD WILLIAMSON: The unfathomable secrets of Great Deep at Thorney

You can walk around it on the seawalls and peer into its hidden depths as much as you like, but you’ll never fathom all its secrets.

The army camp is on one side and the vast channels of the sea are on two others.

Once I saw the body of a roedeer which had become trapped in the mud and been unable to get out.

Some say there are otters there, others say not. Huge numbers of wildfowl find sanctuary along its shores and upon its wide waters and they are left in peace and seclusion.

About once a year I am allowed in, to count all the birds. This is part of monthly north European counts on all wetlands. It is quite extraordinary what is hidden away deep in the reedbeds and the black broad waters and little creeks of the Deeps.

Since the flocks of birds change from year to year, I have repeated this week’s walk with an update on what you may see around the edges this year. At least this gives you glimpses of the interior.

Meadows once grazed by horses to the east of Thorney road are now becoming rough pasture with reeds. The ground is spongy and damp.

The Little Deep circles at the centre of the marsh and joins its bigger brother. By this point the reeds are dense, and hide foxes.

Last week I came across one fast asleep, curled up with his brush over his nose, as I padded silently along the one narrow grass path in the interior. He fled in fright. Not used to humans.

So I came to the Great Deep, being careful not to break through the last curtain of reeds so frightening the massed ranks of birds. Nine cormorants were drying their wings like parsons with umbrellas. A sparrowhawk flew low over one and touched its head with a talon. The cormorant said ‘kaarr’.

More than 100 black-tailed godwits slept in the sun. Curlews and redshanks, grey plover and peewits in their hundreds watched. A few yards from me, scores of wigeon and pintails, gadwalls and teal loafed safe in seclusion. Bearded tits and reed buntings played in the reed heads around me.

In the past I have watched ospreys sitting on the fenceposts eating fish they had caught in the Deeps, unaware of my presence only 20 yards away.

I hoped to see the ream made by an otter’s flat head as it swam submerged among all this tantalising feast of fish and fowl.

This was to be only half of what was on offer to me this memorable day in the Deeps. The other half on the west side of Thorney road is recounted in this week’s walk.