The ghost forest grows in valleys among soul sand.
Following the lava rivers down to the ocean where fortresses can be found.
Where upper lava rivers meet lower terrain, large lavafalls form.
Above the valleys and oceans, narrow layers can be used to traverse the inhospitable terrain.
Fortresses are build primarily above valleys. Scaffolding improve access to the valleys from the layers above.
Some warped forests have grown older and taller than ever before.
Vast areas of lava oceans only split by pillars. Legend has it those might be of interest to miners. Gravel beaches form the edge of the oceans.
Sometimes low elevation rivers form canyons through higher terrain.
Smaller caves can be found below higher terrain.

Completely overhauled Nether: Lava rivers on 2 heights with lavafalls between them, proper valleys, oceans, and new biomes and structures.