After a day of serious Scottish mist and gloomy skies, it was a relief to awaken to bright sunshine. By 06:45, Endeavour had already anchored in Loch Carloway, in the NW corner of the Outer Hebridean Island of Lewis, and we Zodiaced across the bay to make a landing - our destination the magnificent Brock about a mile down the road. These are round fortified dry-stone towers, of which about 500 are known throughout Scotland, all date from 2300 to 1400 years ago. Although the tower on Mousa (Shetland) is the most complete example, the Carloway Brock is the most impressive one in the Outer Hebrides and is none the less so for being partly dismantled on one side. This important archaeological relict is in a commanding location overlooking crofts and the distant coast where a family of ravens was wheeling in the wind. Then it was back for a hearty breakfast while Endeavour repositioned in East Loch Roag for our visit to another ancient site.

Our excursion to the famous Standing Stones of Callanish involved a 3-mile journey by Zodiacs to the quay. The conditions could not have been better. A cold front had cleared the air and fleecy clouds were scattered across the sky. The road, which led to the Visitors Centre and Standing Stones, skirted the bay and was bordered by golden king cups, yellow flags and pink thrift.

The Standing Stones were indeed extraordinary. The slabs themselves are of local origin - Lewisian Gneiss, formed 3000 million years ago from the oldest rock in the British Isles. The ceremonial stones are arranged in a central circle with four rows radiating from the centre at right angles. One is a double row that forms a kind of processional avenue. Archaeologists have revealed that the first stones were erected 5000 years ago, and the latest well over a thousand years later. No one knows for sure what significance these stones had for the farming people who erected them. Perhaps they were a monument dedicated to the moon!

The light was glorious and excellent for photography. And the view of the glacier-carved landscape alone was worth the journey. As ever, the birds were busy in the crofts. Golden plovers in their resplendent breeding plumage could be seen from the perimeter path around the Stones. Starlings - that harbinger of the northern spring - were busy feeding their young in the dry stone walls. One hungry brood was being fed worms every two and a half minutes indicating a daily workload for the parents of at least 300-plus visits a day! Cuckoos, wheatears, a buzzard and a merlin (our smallest falcon that feeds on meadow pipits) greenshank and dunlin were also observed in this delightful location.But it was the afternoon that had the greatest treat in store - a circumnavigation of St. Kilda - the granite remains of a 60 million-year old volcano 50 miles out in the North Atlantic.

Owing to foot and mouth restrictions, no landing on the island was possible to safeguard the flock of ancient Soay sheep, so the best we could hope for was a pass by the stupendous cliffs and the lofty stacs on which tens of thousands of seabirds nest. We were not disappointed. The conditions were ideal, with a relatively calm sea, brilliant sunlight and a cloud base well clear of Conachair - at 430 metres, the highest point of St. Kilda, and the highest cliffs in the British Isles. Captain Saeterskog nudged Endeavour very close to Bororay and the 750-ft high pinnacle that is Stac Lee. With 65,000 pairs of gannets occupying every ledge and the steeply sloping summit, it was a breathtaking spectacle as befits the largest gannetry in the world. One could only stand in amazement at the exploits and steel nerves of the men and boys of Hirta who used to climb these treacherous rock faces to kill the gannets for food. The next port of call was School Bay on Hirta - the main island - and the location of the settlement that was abandoned in 1930. When we arrived, the bay was like a millpond. Viewed from a few hundred yards offshore, the old stone houses, storage cliets and walled enclosures were picked out by shadows cast by the sinking sun. Soay sheep grazed on the lush green turf, while around us, fulmars wheeled and a continual traffic of puffins commuting to and from their burrows. Thus ended a terrific day.