dave2008
Legend
They are discussed (from Chapter 2 of the 2014 DMG):
Between the Sea of Fire (on the Plane of Fire) and the Sirocco Straits is a towering firestorm called the Great Conflagration, sometimes called the Plane of Ash. Howling winds from the Plane of Air mix with the cinder storms and lava of the Plane of Fire to create an endless storm front — a wall of flames, smoke, and ash. The thick ash obscures sight beyond a few dozen feet, and the battering winds make travel difficult. Here and there, ash clusters into floating realms where outlaws and fugitives take shelter.
The border region between the planes of Water and Earth is a horrid swamp where twisted, gnarled trees and thick, stinging vines grow from the dense muck and slime. Here and there within the Swamp of Oblivion (also called the Plane of Ooze), stagnant lakes and pools play host to thickets of weeds and monstrous swarms of mosquitoes. The few settlements here consist of wooden structures suspended above the muck. Most are built on platforms between trees, but a few stand on stilts driven deep into the muck. No solid earth underlies the mud of the swamp, so houses built on poles eventually sink down into it.
A great range of volcanic mountains called the Fountains of Creation is home to azers. These rocky peaks curl from the edge of the Plane of Earth around the Cinder Wastes toward the fiery heart of the plane. At the edge of the plane, the mountains are also called the Plane of Magma. Fire giants and red dragons make their homes here, as well as creatures from the neighboring planes
The Frostfell, also called the Plane of Ice, forms the border between the planes of Air and Water and is a seemingly endless glacier swept by constant, raging blizzards. Frozen caverns twist through the Plane of Ice, home to yetis, remorhazes, white dragons, and other creatures of cold. The inhabitants of the plane engage in a never-ending battle to prove their strength and ensure their survival.
