Mothering Sunday Islands
The Mothering Sunday Islands is a group of atolls in the Great Southern Pelagic Ocean. The most significant of these is the island and country known as Nation. Before the last ice age the area was home to an advanced civilisation which was washed away by the rising ocean.
If the name strikes you as odd, consider all the islands named after the holiday or feast on which they were discovered by European explorers. The discovery of the Mothering Sunday Islands just happened to coincide with one of the lesser festivals.