The Tidal Swing

The coast you are working with

This is a limestone coast with a tidal range of up to ten metres at spring tides, which is among the largest in Britain. The rocks are Carboniferous Limestone, the same formation that runs under the Bristol Channel, and the sea has cut it into a series of small bays, headlands and caves. Two of those caves matter here.

The reason the tide matters so much is not that the caves flood — they all flood, at every high water. It is that the approach to them crosses a rock shelf which is exposed for a different length of time depending on which tide you get. On a neap low, the shelf is dry for about four hours. On a spring low, it is dry for six or seven. On a spring high, the same shelf is under three metres of water and moving fast.

Stage one: the shelf

From the clifftop path, drop to the shelf by the stepped gully. The first container is a micro in a fissure at the landward end of the shelf, at chest height, tucked into a solution hollow that faces away from the sea. It contains the bearing and distance to stage two.

Check your tide before you commit to the shelf, not after. The gully you came down is the only way back up at this end, and it is cut off first.

Stage two: the cave mouth

Stage two is at the mouth of the larger cave, not inside it. The container is a capsule wedged behind a block at the north side of the entrance, roughly two metres in from the drip line. This is the one that gets wet in a big sea: it sits in the spray zone at spring high water and the container has been replaced twice.

Do not go deeper into the cave. It narrows after about fifteen metres, the floor is uneven and partly sand-covered, and the roof has loose material. There is no cache and no view worth the risk.

Stage three: the final

The final is a micro on the headland beyond the second bay, reached by a scramble up a rock ramp that is only safe when the swell is low. The route from stage two crosses a boulder beach; at anything above a moderate swell, the boulders are wet and the crossing becomes dangerous.

From the headland, the logbook container is at knee height in a deep fissure on the landward side. Bring a pen — the container holds nothing but a rolled logbook.

Tide planning

Plan the round trip to finish at the shelf before the tide turns, not at the final. The commonest mistake here is to reach the final at a neap low and find the shelf already covered on the way back — it adds a two-hour wait on a cold headland, or a scramble that people have been injured attempting.

Terrain and footing

• The limestone is undercut in places along the shelf. Keep to the upper level and do not walk beneath the overhangs.
• Wet limestone here is polished by sand and very slippery. Boots with a soft rubber compound grip better than hard-soled shoes.
• The boulder beach between stage two and the final moves in winter storms. A route that worked last year may not exist this year.
• There is no phone signal in either bay.

After the find

Three Cliffs Bay, half a mile east, has the best view in Gower and a salt marsh behind it that is worth the detour at low water. Pennard Castle above the bay is a Norman ruin with a great deal of sand inside it and a good story about why.