Ice breaks off the Breiðamerkurjökull glacier and ends up in this lagoon, before floating down a small river and into the ocean (or landing on Diamond Beach).
From the Album: Iceland Part 2
Day three in Iceland took us east from Vik out to Diamond Beach at Breiðamerkurjökull Glacier and Jökulsárlón glacier lagoon. The Sun made a showing while we were out there but quickly retreated as we drove back west to Selfoss, stopping at Fjaðrárgljúfur Canyon. I put together a video of this part of the trip: Diamond Beach and Glacier Lagoon.