The hook
Icebergs the size of houses break off a glacier and drift across a lagoon that didn't exist a century ago, then wash up as polished blocks on a black-sand beach.
01Why it's worth it
Jökulsárlón is where a tongue of Iceland's great ice cap meets the sea. As the glacier retreats, and it has retreated fast, huge slabs calve off its snout and float in the meltwater lagoon left behind, milk-white and electric blue by turns depending on the air trapped inside, sometimes with seals hauled out among them. The lagoon only started forming in the 1930s and has quadrupled since the 1970s. It is now the deepest lake in the country, and watching centuries-old ice topple into it is about the most direct look at a warming climate you can get. Downstream, the surf grinds the smaller bergs into clear boulders and strands them on the black sand they call Diamond Beach.
02How to experience it
It's on the ring road in the southeast, a long drive of four to five hours from Reykjavík, best folded into a wider south-coast trip. You can walk the shore for free, take a boat out among the bergs in summer, and cross the road to Diamond Beach. Any season works; winter brings darker, emptier drama and a chance of northern lights over the ice. Dress for the wind coming off the ice, which never lets up.