This walk takes us over the hills and clifftops of Orkney’s high island to the Old Man of Hoy, Britain’s tallest sea-stack, with tremendous views of the north Scottish coast and Scapa Flow. The walk is partly on roads and tracks, partly over rough and exposed hill. Take boots, warm clothing and a waterproof, midge cream, sandwiches and a thermos.

From Moaness pier, follow the made-up road inland until it turns sharply right. Continue along the track past Sandy Loch, a reservoir for Flotta, the oil terminal island and into a classic example of a glaciated valley which leads to Rackwick on the Atlantic coast. Ward Hill, Orkney’s highest summit and the site of a warning beacon from Norse times onwards, rises to the left. To the right is Cuilags, the hill from which we shall descend at the end.

Rackwick is the only community on Orkney which looks like a traditional crofting township in Shetland or the Hebrides. Life here, based on fishing, primitive farming and the hazardous collection of birds and their eggs from near-vertical cliffs was always precarious. Rackwick was abandoned sometime after l937, when the two last pupils at its tiny school were drowned. Today there are holiday homes in some of the former croft houses.

Now take the cliff path which climbs westwards on to a shelf of moorland beneath the Cuilags. Gradually the head of the Old Man comes into view; but the full majesty of this massive sea-stack becomes apparent only at the very last moment when you reach the cliff edge.

The stack is a pillar of red sandstone the height of St Paul’s Cathedral. It stands on a protective foundation of hard volcanic lava and so escapes more or less instant demolition by the Atlantic. Nevertheless, the days of this spectacular feature are numbered. In 1750 it had not yet been formed, in 1818 it was twice its present size. One winter night, sooner or later, it will fall. So take your pictures; this may be your last chance.

Northwards again the path becomes less distinct as it climbs to the top of Britain’s highest vertical cliffs at St John’s Head. Layer upon layer of red, ochre and brown Devonian sandstones drop more than 350 metres straight to the ocean. An immense southward view embraces the whole Sutherland coast and the remote northern summits: Ben Loyal, Ben Klibreck, Ben Hope and the Cape Wrath hills.

Turn north-east and strike across the shoulder of the hill inland from St John’s Head to reach the back-wall of a spectacular corrie, named Enegars on the map. Continue east and south, holding to the highest ground, until you reach the Cuilags summit, 433 metres. This is surely one of Britain’s finest viewpoints.

Immediately below is a typical Scottish estate landscape around Hoy Lodge: large house, straight roads, scattered farms. Hoy has always been an estate island, whereas most of Orkney is owner-farmed. In the channel between Gramesay and Hoy lie the remains of a blockship, sunk here in 1940 to deter U-boats. South-east of Graemsay, Scapa Flow opens out, a land-locked sea bounded on its farther shores by Orkney Mainland and the South Isles. Today the flow is usually deserted, but it is easy to imagine it filled with ships: the Royal Navy in two world wars, the 74 ships of the Kaiser’s navy which came here to surrender in November 1918 - and to be scuttled the following June. Far to the east, a buoy marks the spot where a daring U-boat commander torpedoed the battleship Royal Oak in October 1939 as she lay at anchor and amazingly unprotected in the Flow. Eight hundred men died with their ship that night.

From Cuilags the walk descends steeply but without rocky obstacles to the track beside Sandy Loch and so back to Moaness pier.

Patrick Bailey is the author of Orkney in the Pevensey Island Guides series (David Charles)

Distance 12 miles

How to get there Early morning ferry from Stromness to Moaness pier, return by late afternoon ferry.

OS Landranger Sheet 7

Orkney Tourist Board 01856 872856.