Lagarfljót is about 140 km. long flood or river, consisting mostly of glacial water. The innermost section forms a lake Lögurinn. The depths of the lake descend to 112 m. with the bed of the lake as deep as 90 m. beneath sea level. The Lögurinn is home to the legendary monster serpent Lagarfljótsormurinn, first mentioned in 1345. It was considered a bad omen if the curved formes of the monster were spotted above the of the water. In recent years it has not revealed itself so often, yet the Lagafljót serpent is truely unpredictable.