I visited this amazingly serene place many years ago when I camped alongside the lake. Lying awake in bed, there was almost silence apart from the sound of the wind and the occasional creaking and groaning of the icebergs and glacier. Ice broken off from the Breidamerkurjokull glacier forms large, strange sculptural shapes which float on the pristine, clear glacial water.
Close to highway number one about 350 km east from Reykjavík. Watch out for the aggressive skuas. Depending on the time of year, there can be lots of bird noise. There is a popular boat trip around the lake, so this is best heard when the other tourists have gone home.