According to the myth , Odin took Loki 's three children , Fenrisulfr , Hel and JÃ rmungandr . He tossed JÃ rmungandr into the ocean that surrounds Midgard . According to the Prose Edda , Odin took Loki 's three children , FenrisÃ lfr , Hel and JÃ rmungandr , and tossed JÃ rmungandr into the great ocean that encircles Midgard .