A nebula in the Delphic Expanse containing the entrance to a subspace corridor guarded by the Kovaalans, which Enterprise had to pass through to reach its meeting with Degra.
The Kovaalan nebula features in the Enterprise episode E². In 2154 Enterprise needs to get to a rendezvous with Degra in time to address the Xindi Council, and the only quick route is a subspace corridor whose mouth lies inside the nebula. The Kovaalans, who control it, attack any ship that comes near.
As Enterprise approaches it is met by a second, battered Enterprise under a captain named Lorian. He explains that in his history the ship's passage through the corridor threw it back about 117 years, and that his crew are the descendants of Archer's.
The two ships fight their way past the Kovaalans together and adjust Archer's engines to avoid the accident. Archer's Enterprise comes through safely, and the fate of the other is left unknown.