Deep Heaven is outer space and the home of the eldila. Weston admits that he’s been taken over by a demonic being when he mentions having been to Deep Heaven before.
Deep Heaven Term Timeline in Perelandra
The timeline below shows where the term Deep Heaven appears in Perelandra. The colored dots and icons indicate which themes are associated with that appearance.
...eldila, the Tellurian eldils, but they’re generally hostile to people and to the eldils of Deep Heaven . Earth, in fact, is effectively under siege. The hostile eldils’ occupation of earth explains... (full context)
...This is because the “two sides”—the bad eldils occupying earth and the good eldils of Deep Heaven —are beginning to reveal themselves more clearly through their influences on Earth’s affairs. In addition,... (full context)
...beasts by teaching them, and someday tear the curtain of the sky asunder so that Deep Heaven can be seen. At that time, Maleldil will make them different creatures, something like eldila.... (full context)