Taenerus

Taenerus was once part of the Nether Realm until earthquakes and rising seas drowned the narrow, low land bridge that joined them. Legend makes its southern approaches very dangerous because of the shallows of the Taenerus Reef, which sits between the Nether Realm and the paired islands of Aconcagua and Gualagula, commanding the passage from the Atlantean Ocean to the Stygian Sea.

Most of the old legends about it are plainly absurd, but all agree it held rich deposits of precious stones, and Atlantean ships are known to have called regularly in the First Age. Atlantean sorcerers are also said to have tried breeding plants and animals that could thrive there, with mixed results, and strange monsters are believed to roam the rocky island still.

The neanderthaloids of Aconcagua and Gualaguala revere Taenerus as the place where dead heroes go to triumph forever over its monsters, and they dread any visit that might loose heroes and monsters alike on the living world, so they do everything they can to stop strangers from going. The island is harsh and savage, with dry, bleak summers and winters of fierce blizzards and subzero cold.