Midgard is a realm in Norse mythology. It is the home of mortals. Midgard is surrounded by a world of water or ocean. The ocean is inhabited by the great sea serpent Jörmungandr. It is a world between Asgard, the land of the gods (Aesir) and Helheim (Hel), the land of the dead. Midgard was connected to Asgard by the Bifrost Bridge, which is guarded by the god Heimdall.