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Trough Cove [North Entrance]

Trelung Bay, Fowls Heugh, Aberdeenshire.

A fine cave system with 3 entrances(2) and 4 tunnels plus two extension tunnels.

The two main tunnels run approx southwest from the north entrance, and northwest by west from the south entrance, meeting at approx NO 87822 81408. This route from the north entrance to the south was just navigable from July to September 2019 about 1h30 before a 3.8 m high tide. However, when this was attempted in July 2020, there was found to be a middle pebble beach blocking the south part of the north tunnel (Photo 4). This remained at least until the end of Aug 20. But by 8 Oct 20, it had almost entirely been washed away - presumably by 3m + northeast swell on the previous weekend. So this beach appears to be there, or not, depending on the most recent stormy weather. On 20 Mar 21, there was no middle beach.

By 18 July 21, the middle beach had reformed, blocking the S part of the N tunnel. There appeared to be a lot of pebbles on the beach of the west tunnel (on the north side of the dividing pillar). A landing allowed the west tunnel to be measured and photographed and, standing on the middle beach a 'missing slice' cavity was found on the south side of this beach, fairly high up and sloping down towards the southwest.

This beach was in place all through '22 and then found to be absent on 18 Feb 23. On 29 August 24, at tide level 2.3 m ACD, this beach was awash - so with a tide level of 2.6 m or more, it would have been easily kayak navigable.

There is a south-facing pebble beach ending about 20m northwest from where the north and south tunnels join. On 29 August 24, the pebble beach was almost completely scoured of pebbles, leaving mostly bedrock - see photo 13.

The north entrance is tall and fairly narrow. A side tunnel goes approx west by south, curving to southwest by west, for 28m from about half way along the main (north) tunnel and has its own north-facing pebble beach. Part of this may be seen in photo 3. See also photos 9 to 11.

There is a wide, curved passage round a massive rock pillar from the middle entrance to the middle of the south tunnel. This passage is presumably the one through which one can sail (OS name book).

If you are afloat at the join between the tunnels from the south and mid entrances and look up about north-northwest to where the wall meets the ceiling, there is a large sheet of small flowstones. There are some small stalactites high in the north tunnel (photo 7) and white flowstone patches over large areas of walls and ceiling which are best seen with a good light.

In Aug 2020, two extension tunnels were found from the S pebble beach. One going on 8m on the line of the south tunnel. The other a 38m rift tunnel on the line of the north tunnel, but curving a little bit west. See entry for the south entrance for photos.

The north tunnel and its extension appear to have been formed on a fault. See scan from a BGS map showing this fault.

This is the second longest sea-cave (total tunnel length) on the mainland coast of Scotland to date, and third, after Hol o' Boadie (Papa Stour, Shetland) and Smoo Cave (Durness), in the whole of Scotland.

The cave is much frequented by younger grey seals in the summer months - as are the neighbouring caves north and south. Grey seals almost certainly breed here in autumn.

Alternative Names: Throch Cove, The Great Cave

Notes: Access: by sea S from Stonehaven or N from Catterline.

One through passage is available in the top 3/4 of the tide and low to moderate swell between the middle and S entrances. A second, much longer one of approx 179 m is available in the top 1/4 of the tide and low swell between the N and S entrances provided there is no shingle bank blocking the SW half of the N passage. It was observed unblocked on 18 Feb 23. See above for more info.

1. "A large cavern under the cliff through [which] a boat with mast and Sails set can pass: there are four mouths or entrances into this huge cave."

From the above it is clear that 'Cove' in 'Trough Cove' means 'cave' rather than the normal dictionary definition of 'small bay or creek'. This appears to be quite a common usage in this part of Scotland.

2. The OS name book says 4 entrances and the Canmore current OS Levels 10 - 12 have 4 caves indicated. However, it is clear from Canmore aerial (and on site) that although there are two approaches to the S entrance, these join outwith the overhang of the cliff above. Comparison of the current Aerial layer with the 1st Ed 6" OS on Canmore suggests that the cliff edge over Trough Cove S entrance may have moved W by 12 m or so in the last 150 yrs.