Only tool with multi-layer caves
Underdark Map Maker
Build multi-layer cave systems for your D&D campaigns. Three Underdark depths with vertical connections, procedural cave generation, and fog of war on every layer.
Free to try. Underdark layers included in the Game Master plan.
Try it — click the tabs or gold triangles to switch between depth layers.
Three Depth Layers
Upperdark
The first layer below the surface. Fungal forests, underground lakes, crystal caves, and cavern networks where Drow outposts and Duergar settlements thrive. Most accessible to surface dwellers.
Middledark
Deeper and more dangerous. Lava tubes, mineral veins, bone-strewn caverns, and chasms that split the earth. Home to ancient horrors and things that have never seen sunlight.
Lowerdark
The deepest reaches. Abyssal voids, magma seas, alien crystal formations, and fungal depths where reality thins. End-game territory for the boldest parties.
Connect layers. Generate caves.
Link layers with cave entrances, staircases, shafts, chasms, and magical portals — four connection types that let your party descend naturally through your world.
Generate entire cave systems with one click using noise-based algorithms. Biome-aware terrain places fungal forests near water, crystal caves near mineral veins, lava in the deep. Every generated cave is fully editable — tweak anything by hand.
Each layer has independent fog of war. Reveal the Upperdark without spoiling what's below. Dynamic vision adapts to terrain, weather, and time of day.
12 Cave Terrain Types
Cavern, Fungal Forest, Crystal Cave, Underground Lake, Lava Tube, Mineral Vein, Bone Yard, Chasm, Abyssal Void, Magma Sea, Fungal Deep, Stone Floor — each with unique colors and icons, purpose-built for subterranean worlds.
Start Building Your Underdark
No other hex map tool offers multi-layer cave systems. Try the editor free, then upgrade to unlock Underdark layers, fog of war, and cave generation.
Frequently Asked Questions
Can I create Underdark maps online for free?
Yes — Hexer is free to start. The Underdark layer system is a Pro feature (€4.99/month), but you can explore the editor and surface map tools for free before upgrading.
How many Underdark layers does Hexer support?
Hexer supports three subterranean depth layers — Upperdark, Middledark, and Lowerdark — plus the Surface. Each layer has its own hex grid, terrain, notes, fog of war, and connections to adjacent layers.
Can I connect Underdark layers to the surface?
Absolutely. You can place vertical connections like cave entrances, mine shafts, staircases, and portals between any adjacent layers. Players can navigate these connections in the shared live view.
Does fog of war work underground?
Yes. Each Underdark layer has independent fog of war. You can reveal hexes per-layer as your party explores, keeping undiscovered caverns hidden. Fog state is preserved between sessions.