We are told that Ireland was once an island covered in great forests and in those forests the mighty oak was the dominant tree. Today this is hard to envisage with oaks a rarity, generally confined to rocky ravines like the Ness Woods or Roe Valley Country Park. Even in these places they tend to be small with limited canopies. This walk in glorious Crom estate looks at alternative oak woodlands which hint at the possible true ancient landscape of Ireland.

Murlough Bay is one of our wildest and most beautiful places. If we had National Parks, this area should be part of one. However, it is not pristine wilderness – its rocks, woods and plains tell a story of long human occupation, farming, mining and spirituality – all adding richness to the fascination of this unique place.

Karst is a scientific term for a kind of landscape created by limestone and water where the normal behaviours of rivers, rocks and landforms don’t apply and indeed are turned almost inside-out! Rivers abruptly vanish underground to later re-appear at some apparently arbitrary point. Dry hollows, sink holes, rocky valleys and heights form a strange, sometimes dangerous alien landscape and everywhere is underlain with an ultra complex 3-D maze of wet and dry passages and caverns. There is nothing else quite like it and in the Marble Arch / Marlbank area of the Fermanagh Geopark we have a superb example.

This Karst walk follows a river upstream from deeply wooded Cladagh Glen, past the lower entrances to the Marble Arch cave system, up onto the Marlbank plateau and then along an initially dry mountain valley, past a sinkhole to join the Owenbrean river as it flows from its head waters in the blanket bogs of Cuilcagh Mountain.