The waters of the Erne Lakelands are best known nowadays for leisure pursuits like boating and fishing. But millions of years of development have gone into creating this landscape.
Most of the rocks under these lakes date from the Carboniferous Period, between about 350 million and 300 million years ago. This was when the warm and shallow Carboniferous sea first advanced across this part of Ireland.
The view we're seeing now is part of the Castle Archdale Country Park, which covers about 230 acres of this part of Fermanagh.
This region is abundant in ancient and not so ancient historical features. There are monastic sites such as Devenish Island, the remains of the Archdale manor House, built in 1773, and the effects of the Second World War. Castle Archdale was the main base for the flying boats that took off from here to protect allied convoys in the north Atlantic.
Further down Lower Lough Erne we come to some of the huge number of islands that dot the water line. At the last count, there were 154 of them. The lough lies in a deep glacial trough, and everything here - from the alignment of the banks to the position of the islands - was determined by the movement of the ice.
Along the shore the bird life includes lapwings, redshanks, curlew and snipe, as well as a unique colony of breeding Sandwich terns.
On Devenish island, we're enjoying what might be called a bird's eye view of a church site that was founded by St Molaise in the 6th century. It was raided by the Vikings in 837, burned in 1157 and rebuilt as a parish church in the Middle Ages.
The lower church has a beautifully moulded south window dating from around 1300. From the 30-metre tower seen here in the background, the monks were able to judge the appearance and intention of approaching strangers.
Most of the rocks under Lough Erne date from the Carboniferous Period, between about 350 million and 300 million years ago.
Along the shore, the bird life includes lapwings, redshanks, curlew and snipe, as well as a unique colony of breeding sandwich terns.
The monastic site on Devenish Island was founded by St Molaise in the 6th century.