Living underneath our feet along the coast and islands of western Donegal is a large collection of spectacular and little-known granite sea caves. The islands of Umphin, Owey, and Arranmore contain perhaps the more impressive and larger of these caves.
Access to these little known underground kingdoms is by boat and calm seas are required for safe access.
A few weeks ago Fiona nic Fhionnlaoich, Paulina Kaniszewska, and my good self, made a very early morning paddle by sea kayak out to the Stag Rocks, 7km west of mainland Donegal. It was on our return to mainland Donegal we made a wee detour into the sea caves on the northeast side of Owey Island. As the sun was in its midsummer sunrise position, direct sunlight was shining directly into mouths of most of the caves on this side of the island. This created the most spectacular Blue Lagoon effect in the sea water inside the caves. This affects the sea water by making it appear invisible and any object in the water looks like it is suspended in air. An underground infinity pool is the resulting effect.
The effect of direct sunlight at the correct position and angle into a sea cave causes what I call the Blue Lagoon effect. The sea water in the direct sunlight area glows very brightly the same colour as the sky outside. This, in turn, illuminates the cave walls and roof. In a granite cave, the walls will glow all the colours of the minerals contained within the rock. The whole effect looks like an explosion of light and is a surreal natural phenomenon to witness first hand. This effect happens in any sea cave in which the sunlight enters the cave mouth at the correct angle. Its just a case of being in the right place at the right time.
We made a cunning plan to return as soon as possible with underwater filming toys. Time was not on our side as the sun only hits these caves are the correct angle for a short period at sunrise around mid-summer.
Swimming in a Pool of Light film
On 26th July 2018, Fiona and I made another early morning visit to the largest of the Owey sea caves. The forecast was for heavy rain and thick cloud from 0900hrs but there was a promise of a good clear sunrise prior to the downpour. As Fiona said, "half a chance is better than no chance." We paddled out from the wee pier at the golf club on Cruit Island alas on the journey out no sun was in attendance and a huge ominous lump of grey cloud sat where the sun should have been.
We arrived in our chosen cave and paddled around for about an hour in the increasing gloom and as if by magic there was an explosion of light all around us. The sea turned bright green/blue and the walls and roof began to shimmer a dozen different colours as bright sunlight bounced around the inside of the cave. The walls and ceiling of the cave began to shimmer in reds, purples, oranges, and pink as the sea glowed a bright greeny Blue.
Fiona jumped in and went for a swim whilst I filmed from an excellently positioned ledge above the glowing water in the cavern. We swam and filmed for approximately 40 minutes until the sun went behind a sky now filled with clouds and the cave returned to its underground gloom.
With a little bit of planning, nautical guile and good luck, it is possible to visit almost any sea cave at the right time and conditions to witness this Blue Lagoon effect. What you will experience is a surreal infinity pool swim in which It feels you are swimming in Light.
Paddling into the Cave of Light
Fiona swimming in the Infinity Pool
The underwater view
Fiona swimming in the Pool of Light
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