Breiðamerkurjökull is an outlet glacier of the larger glacier, Vatnjökull, located in southeastern Iceland. Emerging as a tongue of the Vatnajökull, it ends in a small glacial lagoon, known as Jölkúsarlón. Breiðamerkurjökull is among the largest glacier tongues in Iceland and the flow of ice has a southerly direction away from the main icecap Vatnjökull. Over time, the glacier has gradually been breaking down and receding, increasing the size of the lagoon. Up to the turn of the 19th century, the glacier tongue advanced to within 200 metres from the sea but has retreated considerably, especially after 1930, creating the greater part of the Glacial Lagoon. At the ice calving site icebergs break away from the tongue of the glacier and begin a slow drift in the icy waters of the lagoon. Slowly the ice drifts to mouth of the lagoon and eventually reaches the ocean.