Layers:

Abyss: includes layers of Azzagrat, Durao, Thanatos
Acheron: Avalas, Thuldanin, Tintibulus, Ocanthus
Arborea: Olympus, Ossa, Pelion.
Arcadia: Abellio, Buxenus, Nemausus
Baator: Avernus, Dis, Minauros, Phlegethos, Stygia, Malbolge, 
Maladomini, Cania, Nessus
Beastlands: Krigala, Brux, Karasuthra
Bytopia: Dothion, Shurrock
Carceri: Othrys, Cathrys, Minethys, Colothys, Porphathys, Agathys
Elysium: Amoria, Eronia, Belierin, Thalasia
Gehenna: Khalas, Chamada, Mungoth, Krangath
Gray Waste: Oinos, Niflheim, Pluton
Mount Celestia: Lunia, Mercuria, Venya, Solania, Mertion, Jovar, 
Chronias
Pandemonium: Pandesemos, Cocytus, Phlegethon, Agathion
Ysgard: Ysgard, Muspelheim, Nidavellir