The shimmering pools that lay beneath the mountains of Ered Wethrin, on the northern borders of Beleriand, from which the torrent of the River Narog flowed. They were famous for their beauty, and for the power of Ulmo that protected them. Some twenty years after the Return of the Noldor to Middle-earth, their Feast of Reuniting - the Mereth Aderthad - was held on the banks of Ivrin's pools, and centuries later their healing waters brought Túrin back from madness. Glaurung the Dragon came to Ivrin as he travelled to attack Nargothrond, defiling the waters as he passed to leave a region of frozen swampland.