Jökulsárlón is an amazing place. Recently it has been discovered that the lagoon is really a fjord that was carved out by the glacier. The eastern part of the glacier eroded the sediments of Breiδamerkurjökull to a depth of 300 m below sea level. The river carried the sediments forward. That created a deep basin. This would have been impossible if the river had not carried the sediment. Without that river the basin would have been plugged up with sediment.
Oddly, the lagoon is actually privately owned. So you could buy it. Wouldn’t you like to own a lagoon filled with icebergs? To me it was the most surprising sight in Iceland. I never expected to see them here.
Some of the icebergs were beached. We could walk partly around them. When icebergs land on a black sand beach that is an incredible sight. I could not get enough photographs of them. They were amazing.
From 1890 to the present the glacier has retreated. The large chunks of ice break off the glacier and are carried by the current of the river to its mouth where many of them get stranded on the bottom. Those that are floating only show about 1/10thof their mass above the water. The rest is under the water. Tidal currents move the bergs back and forth and often they scrape the bottom depending on their size and the depth of the river. The smaller ones drift out to the sea.
Most icebergs are milky white except for the dark sediment that they carry, but some have a bright blue color caused by the interplay of ice crystals and light. Often seals are seen in the bay but I was not lucky enough to see any. Shoals of herring often enter the bay providing a feast for birds such as Artic terns that come here in large numbers.