Take a boat out on the Erne from the town harbour

Walk Butler Street down to the Diamond and round the town's buildings

Work out why the isthmus made this the crossing point

Follow the Shannon–Erne Waterway south and see how far it would take you

Béal Tairbirt means the mouth of the isthmus — the narrow neck of land between the Erne system and the drumlin lakes, which is why a town grew here and why it is now one of the main boating harbours on the Shannon–Erne. The main street runs down to the Diamond with the town's buildings around it, and below that the river. Since the Shannon–Erne Waterway reopened in 1994 you can take a boat from here the whole way to Limerick.

Belturbet: The Mouth of the Isthmus on the Erne

Paddle a multi-hour canoe or kayak route through the interconnected lakes of the Lough Oughter complex

Reach Drumlane Abbey near Milltown and find the round tower beside the ruined Augustinian church, on a site that goes back to St Columba and St Mogue

Photograph the round tower's doorway, set several metres above ground level — built high to hold the near-foundationless tower together rather than to keep raiders out

Walk the ruined nave of Drumlane's medieval church beside the tower and find the graveyard's oldest legible headstones

Christianity is said to have come to Drumlane around 555 with St Columba, and St Máedóc — St Mogue locally — founded the early monastery; what stands by the water now is a ruined Augustinian church and a round tower. It stands on the edge of the Lough Oughter lake complex, one of Ireland's largest connected inland waterway systems.

Drumlane Abbey and the Cavan Waterways

Walk the woodland trails down to the shore of Upper Lough Erne

Walk the old parkland trees of the demesne above the shore

Take a boat out among the islands and reedbeds of the upper lough

Look at riparian woodland growing straight into the water and work out why so little of it is left

Crom is 1,350 acres of nature reserve along the shores of Upper Lough Erne, mostly riparian forest — woodland growing right down into the water, which is a habitat that has almost vanished from Ireland. The National Trust runs it as one of three Fermanagh estates alongside Florence Court and Castle Coole. It is quiet in a way that few places are: islands, reedbed, old parkland trees, and water on every side.

Crom: Riparian Forest on Upper Lough Erne

Get out on Lough Oughter by boat or kayak to reach the castle island

Walk right round the circular keep on its island

Find out how a castle came to be built on what may be a man-made island

Walk the trails at Killykeen Forest Park on the lough shore

Cloughoughter is a circular stone castle standing on a tiny island in Lough Oughter, four kilometres east of Killeshandra, and the only way to it is by water. The island may be a crannog — an artificial one — with fortification here possibly as early as the 6th century. The O'Reilly chiefs of East Breifne held it for centuries, and Owen Roe O'Neill, commander of the Ulster Army, is said to have died there in 1649. It sits out in the water with no road, no path and no signage, which is exactly why it looks the way it does.

Cloughoughter: A Round Castle on a Cavan Island

Paddle out into the Lough Oughter channels from Killykeen

Walk the forest trails and the lakeshore loops through the park

Work out how a drumlin field turns into a lake with no shape to it

Paddle within sight of Cloughoughter Castle out on its island

Lough Oughter is not really a lake but a flooded drumlin field — water filling every hollow between hundreds of small round hills, so what looks like a lake on the map is a maze of channels, bays and wooded islands with no obvious way through. Killykeen Forest Park sits in the middle of it with 240 hectares of woodland, and the best way to understand the place is from a canoe, working out the route as you go.

Killykeen: Paddling the Lough Oughter Maze

Drive the lake roads north-west of the town and count how many loughs you pass

Walk in Killykeen Forest Park among the drumlins and the water

Find out why the ice left Cavan with this many small hills and this much water

Fish or paddle on one of the loughs — most of them have no one on them

Cavan is the county of the drumlins and the lakes, and the local boast is that there is one lake for every day of the year. The truth is close enough: the ice left a field of small rounded hills, the water filled every hollow between them, and the result is a landscape where the road bends constantly because it has no choice. Lough Oughter is really one continuous flooded maze rather than a lake, and the town sits in the middle of it all.

Cavan Town and the Lakeland Drumlins

Find the round tower and the Augustinian abbey ruins in the town

Stand at the Cross Moyle high cross in the middle of the Diamond

Find the stone sarcophagus said to hold St Tighernach

Look for the pictographic tombstones in the old graveyard

St Tighernach founded a monastery at Clones in the 6th century and his cult spread right across the British Isles. What is left is scattered through an ordinary market town: a round tower, the ruins of an Augustinian abbey, pictographic tombstones, and a carved stone sarcophagus said to be Tighernach's own. In the middle of the Diamond, the town square, stands the Cross Moyle high cross — five metres of sandstone, assembled from the parts of more than one cross.

Clones: The Round Tower, the High Cross and the Sarcophagus

Walk across the Whitworth Aqueduct where the Royal Canal crosses the River Inny

Find the Cistercian abbey ruins on the banks of the Inny

Walk the Royal Canal towpath east or west from the village

Work out how a canal is built to cross a river at all

Mainistir Shruthla — the monastery of the river. The Cistercians founded an abbey here on the banks of the Inny in 1150, from Mellifont, eight years after the order reached Ireland and the ruins are still on the river. Then in the early 19th century the Royal Canal arrived and had a problem: it had to cross the Inny. The answer was the Whitworth Aqueduct, carrying the canal over the river on stone arches, and the trade it brought kept the village going until the middle of the twentieth century.

Abbeyshrule: The Whitworth Aqueduct Over the Inny

Find the O'Cahan tomb inside the priory ruins

Look at the carved figures in the arcade beneath the effigy

Find the bullaun stone under the rag-hung thorn bushes outside

Look at how the 1100s priory sits on the foundations of older churches

The Augustinian priory at Dungiven was built in the 1100s on the foundations of earlier churches, and inside its ruins is the O'Cahan tomb, long said to be that of Cooey na Gall O'Cahan, who died in 1385 — though the effigy itself looks to be late 15th-century work, and may be a later man of the same family — one of the finest medieval tombs in Ireland, with the effigy above and a row of armed figures carved in the arcade beneath. Outside in the graveyard a thicket of thorn bushes is hung with rags: a bullaun stone sits under them, and people still come to it seeking cures for warts.