Marble Arch Caves, County Fermanagh

The tour starts at the visitor centre, where your guide briefs the group on what to expect. You get a hard hat. No helmets with lights - the cave is fully lit with electric walkways throughout. The first stretch descends concrete steps into the gorge where the Cladagh River vanishes underground.

You board a flat-bottomed boat on the underground river. The ceiling drops low in places - not claustrophobia-inducing, but you notice it. The water is black and still. Your guide poles the boat forward while pointing out formations overhead. This section lasts about ten minutes and it is the highlight for most visitors.

After the boat, you walk. The path winds through chambers connected by narrow passages. Stalactites hang from every ceiling. Some are thin as drinking straws. Others are thick columns where stalactites and stalagmites have met and fused over thousands of years. The flowstone cascades look like frozen waterfalls. There is an actual waterfall inside the cave too - you hear it before you see it.

The temperature stays at 9-10°C regardless of the season. Bring a jacket even in August. The air is damp and the walkways can be slippery. Wear shoes with grip, not sandals.

The 154 steps are spread across the full route, not concentrated in one climb. But they add up. If you have knee problems or breathing difficulties, this tour will be hard work. There is no option to skip sections or turn back early once you are underground. The guide sets the pace for the group.

Back above ground, do the Cladagh Glen nature trail. It is free and most people skip it, which is a mistake. The trail follows the river through old-growth woodland where the water re-emerges from the cave system. The contrast between the dark underground and the green canopy above is worth the extra 30-40 minutes.

One honest warning. After heavy rainfall, the underground river rises and the cave closes at short notice. This happens several times each season. If you are driving an hour to get here, phone ahead or check the website that morning. There is no rain threshold published - the decision is made on the day based on water levels. If the cave is shut, the Cladagh Glen and visitor centre exhibition are still open, but the main event is gone.

Marble Arch Caves is on the Marlbank Road, roughly 5 kilometres south of Florencecourt village. You need a car. There is no bus service to the caves and no train station within reach.

From Enniskillen: Head south on the A4 then take the A32 towards Swanlinbar. Follow signs for Marble Arch Caves from Florencecourt. The drive takes about 20 minutes and the road is straightforward. Free parking at the visitor centre with plenty of spaces.

From Belfast: Take the M1 west to Dungannon, then the A4 through Enniskillen. Total drive is around 2 hours 15 minutes depending on traffic through Dungannon. The last section from Enniskillen is well signposted.

From Dublin: Head north on the M3/N3 through Cavan, then cross the border towards Swanlinbar and follow signs. The drive takes about 2 hours 30 minutes. Roads on the Cavan side are narrow in places but manageable.

The car park is right at the visitor centre. No walking from a distant lot. Coaches park in a separate area. On busy summer days the car park can fill by late morning, which is another reason to book an early tour slot.

If you are visiting without a car, you would need to arrange a taxi from Enniskillen. Budget around GBP 25-30 each way and agree a collection time with the driver. There is no phone signal underground, so sort the return pickup before your tour starts.

Enniskillen is the nearest proper town, 20 minutes north by car. It has the widest choice of hotels, restaurants, and supermarkets. For something closer, Florencecourt has one excellent B&B right on the road to the caves. See the full County Fermanagh guide for more accommodation options across the county.