Ginnungagap

Ginnungagap is often referred to as the primordial and misty location between Niflheim, the world of ice, frost, chilly winds and blizzards; and Muspellheim, the world of heat, flames, ignition winds and firestorms. It is said to be the first of the Nine Worlds like creation. It is also a place where dead can be cast into. As suggested by Magnus chase, it is better not to die in a place you cannot pronounce.

The Sword of Summer
It is mentioned multiple times, sometimes as the plane of creation and others as a world of death like Folkvanger.

It is also very unsafe to travel to, is the person is capable of travelling there at all.