Navigation was difficult in the pre-radio/satellite age. Landmarks were critical – at least the ones that didn’t move. Luckily, and I didn’t know this until I visited the area a few years ago, the small entrance to (what is now-a-days called) Dingle Bay has a distinctive cleaved cliff on its western side.
In the second book in The Crossover Series, “Contact,”, my characters travel to southern Ireland in the year 1076 CE (“common era,” aka AD). This broken cliff face provided a distinctive landmark for Larry and his crew when they returned on their second trip. (Which, for those who haven’t read “Contact” yet, didn’t go so well…).
Here’s an overview of Dingle and the surrounding terrain (Ros was the headman back in 1076 CE):
Here is a dramatic (but, unfortunately, out-of-focus) image showing the gap between the mainland and the cleaved cliff edge.
On our recent visit to southern Ireland, my wife and I walked from the town of Dingle (at the north end of the bay) to the entrance at the south end:
The cleaved cliff is just to the right of the tower as seen from this perspective. Note: the tower was built several centuries after the time from of my book. Here’s a view with more detail:
Yes, we had to clean off the bottom of our shoes…in spite of our care.