If you have the chance, don't forget to taste the Korean "flower salt", which is basically salt in crystal flakes, as it naturally forms during evaporation. I haven't yet found a better salt for beef.
Here in Denmark, we make it on the island of Læsø, where the geography helps concentrate the sea water before it is used to make sea salt.
That's the fancy expensive stuff. I use flaky sea salt from 2kg buckets I buy at a restaurant supply store. Much less expensive, works just as well.
In other words, Celtic Sea Salt is more than just NaCl.
We also use salted butter in almost all of our traditional dishes.