There are other caving areas in Scotland that do not posses any caves that are notable enough to be included in this database. The Appin and Arran regions contain many caves, but the longest is only 250 m and the deepest is only 48 m. The book "Caves Of Skye" by the Grampian Speleological Group (1995 ISBN 0 9513901 0 4) shows two caves over 300 m and several shorter. The longest and deepest is 376 m long and 23 m deep. The highest pitch is a blind surface shaft 12 m deep, of which 6 m is usually free climbed.
The Isle Of Man and the Channel Islands both contain some short caves. Many are sea caves.
The chalk coast between Margate and Eastbourne contain a few chalk solutional caves (not sea caves), that are substantially longer than other chalk caves manage to get (chalk is usually too unstable for caves to remain navigable by humans for any significant length). The longest is 350 metres, but is slowly being cut into pieces as the cliff in which it is located is slowly eroded by the sea.
Special interest caves
Pol-An-Ionain in Co. Clare, RO Ireland, is 550 m long. It contains almost no calcite decorations throughout except in the main chamber where a 6.7 m long stalactite hangs from the centre of the ceiling. This is the "Soggy Dishcloth" (officially The Great Stalactite). For a long time it was the longest known free hanging stalactite in the World, and although it has since been superseded by a few others, it is still one of the longest, and still holds the length record for UK and Ireland. What makes it more impressive is the fact that the stalactite is held on by a section of calcite less than 0.3 m square. The cave has now been converted into a show cave (confusingly called 'Doolin Cave'), which it has always been argued would put the stalatite at risk.
Boulby Mine at the edge of the North York Moors is the longest known modern room-and-pillar mine in Britain, with over 1000 km of passage reported in 2015, mostly at 1100 metres of depth, extending under the North Sea. With the deepest point at 1400 metres depth, it is also the equal deepest mine in Britain, matched by Clock Face Colliery in Lancashire. Its shaft is 1150 metres deep, which also appears to be a British record. Several other lengthy room-and-pillar mines exist, and as many are active mines, the lengths and depths will change over time.
Box Freestone Quarries in Mendip is the second longest traditional passage-based mine in Britain, and the longest in England, with over 90 km of known passage. Several sections of the mine were used for military storage during the Second World War, and were off-limits. The largest chamber is 60 m long, 8 m wide and 30 m high. The mine has been in use since Roman times.
Westbury Brook Cavern (or Mine) and Wigpool Iron Mine are both similar to Clearwell Caves in the respect that they both are artificially enlarged natural passages. However, in neither case is the naturally connected passage length or depth known so these are not included in the main database. If I get information to suggest that they should be included, I will include them, but I will need proof.
Dunmore Cave in County Kilkenny, Ireland, holds the undesirable record for the most number of historical deaths in a cave in the Biritish Isles. There is evidence of at least 44 deaths from a Viking massacre in 928 AD, and a further adult and foetus that may also relate to the massacre. The cave is a showcave, with a relatively short length and respectable depth. Most of the interest lies in the archaeological remains.
There are no sea caves in the UK or Ireland long enough to earn a place in this database. The current longest in the UK are West Bay Cave at 400 metres (according to the OS maps) and Holl o Boardie at 330 metres, under Fogla Skerry and Papa Stour in the Shetland Islands, Sandside Head Cave No. 2 on the North coast of Scotland at 230 metres, and Virgin's Spring (aka. Virgin's Well) on Lundy Island at 225 metres (which is partly formed by groundwater, and is not a pure sea cave). The longest known in RO Ireland is Poll Na Seantoine (aka. Pollnashantinny) at about 322 metres, near Ballycastle in Co. Mayo. However, there are also several contenders along the northern Mayo coast, including an estimated 300 metre long sea cave and a 250 metre long sea cave near Geeveraune. These will, of course, change over time, as erosion lengthens the caves or shortens them by removing the cliffs they are in.
The height of the entrances to sea caves is a matter of debate. Overhanging cliffs, or cliffs that progressively funnel into a cave may be enough to constitute a vertical range of 60 metres or more, but it is very hard to define the part that belongs to the cave and the part that belongs to the cliff. Some large arched alcoves are so tall that the alcove's length is less than its height, which makes it hard to even consider this as cave development (such as the alcove in Stookeen Cliff at the Cliffs of Moher, Co. Clare). No extensive studies have been done. As a result, no sea caves are currently included in this database based on the vertical range of their entrance porches. Big examples can be found on the Co. Mayo coast near Belderg (Belderrig), some with as much as 50 metres of height from the sea to the overhanging cliffs above a cave entrance. In these cases, the cave entrances at the bottom of the cliff are much smaller, however. The largest passages are around 50 metres high at their entrances.