Fellsfjara, the east strand at sunrise

Diamond Beach is the stretch of Breiðamerkursandur either side of the Jökulsá river mouth, and the eastern strand — Fellsfjara — is where the outflow and the surf tend to deposit the largest blocks. Ice arrives from the lagoon, gets rolled and polished by the waves, and is thrown back onto sand so dark it reads as black in every frame. Some pieces are the size of a fist, some the size of a car, and the arrangement is different every single day.

Sunrise is the reason to set the alarm. The beach faces roughly south-east, so the first sun comes low across the water and straight into the ice: clear blocks light up internally like cut glass, and a couple placed beyond a berg gets a foreground that glows. Get the camera low and close to a clean piece, or go long and put two figures among a whole field of ice. In the four or five hours of December daylight the sun never climbs high, which means the glow effect lasts most of the short day rather than a single hour.

How much ice there is on any given morning is genuinely unpredictable — a storm can carpet the beach and a warm calm week can leave it almost empty. Say this to clients in advance rather than promising the postcard. Overcast light still works: the blue inside the ice actually saturates when the sky is grey.

The safety rules here are not decorative. This is an open Atlantic beach with sneaker waves — waves that run far higher than the ones before them, without warning — and the surf moves ice: a wave reaching a large block can shift it onto whoever is standing below. Keep upslope of every big berg near the waterline, never pose anyone on or between blocks in the surf zone, never climb onto floating or beached ice, and never turn your back on the sea. Check the swell forecast before the session and be willing to shoot from the dry upper beach instead.