Hello Theo,
Your quest to capture the essence of sea cliffs and rocks from a unique sea-level perspective certainly makes for an exciting photographic adventure.
While it's important to underscore the safety concerns about exploring sea caves - particularly when considering the timing of tides - there are a couple of other locations that might provide the view you're after.
One of them is Murder Hole Beach in
County Donegal. It is a beautifully secluded spot with a sea cave that could offer you that much-coveted sea-level vantage point. However, I should stress that accessing the beach can be a challenge, and it's not a venture to undertake lightly or without company.
Another location to consider is the Ballybunion Cliffs in
County Kerry. Near the town of Ballybunion, these cliffs are dotted with small caves at their base. However, access to these caves can be significantly influenced by tidal conditions, so careful planning around tide times is a must.
In all cases, please remember to prioritize your safety. Check tide times, let others know about your plans, consider going with a companion, and if possible, hire a guide. The natural beauty of these sites is indeed breathtaking, but they can also be unpredictable and potentially hazardous.
Best of luck with your adventures and happy photographing!