Hljóðaklettar, also known as Echo Rocks, is a unique cluster of columnar rock formations located in Vatnajökull National Park in northeastern Iceland. These rocks get their name from the echoes created by the caves and unusual shapes found in the area. Youcan explore the circular trail to see famous formations like 'the Castle,' 'the Troll,' and 'the Church.' Legend has it that many of these rock formations were once trolls turned to stone by sunlight.