At first, the sea was formed around 5.6 million years ago, due to a large-scale flood, but the waters were separated from the Atlantic Ocean by the Strait of Gibraltar, so, in the hundreds of thousands of years that followed, the water spreads dried out almost completely.
The Irish Punt was legal tender in the Republic of Ireland until 2002, when Ireland joined the Euro. This guide outlines the sources for historical exchange rates between the Irish Punt and Pound Sterling. The Irish Punt established by the Currency Act 1927 had a fixed link with Pound Sterling until March 1979.
Although the euro became the currency of the eurozone countries including Ireland on 1 January 1999, it was not until 1 January 2002 that the state began to withdraw Irish pound coins and notes, replacing them with euro specie. All other eurozone countries withdrew their currencies in a similar fashion, from that date.