Glacier lagoon

This is Jökulsárlón 'glacier lagoon'. The glacier is Vatnajökull 'water/lake glacier', the largest glacier in Europe.

The lagoon is brackish, formed from meltwater and chunks of ice from the glacier and seawater.

The icebergs drift towards the sea, getting stuck near the mouth of the lagoon: it's quite shallow there. They break up there and drift out to sea, where they melt.

The tips of the icebergs are white because air gets trapped between the ice crystals. Underwater, the air is squeezed out by high pressure when in the glacier and by the water it's floating in. Water in this state is blue. You can see blue ice above water because the iceberg's centre of gravity changes when chunks fall off.

Some of the icebergs have black bands across them. These are layers of ash from volcanic eruptions over the years. There's no escape from volcanoes in Iceland.