Gígjökull, (“Crater glacier”) a steep glacier–tongue coming down from the crater of the Eyjafjallajökull glacier, hence the name. The lake Jökul­lón in front of the glacier is more than 40 m deep and usually has icebergs floating on it. The glacier is getting smaller every year. The river Jökulsá runs from the lagoon to Markarfljót.