|Hugo Darnaut (1850-1937), Dürnstein on the Danube, 1876|
In Dungeons & Dragons, “dungeon” refers to any underground or interior system of corridors and chambers: rooms connected by hallways. Their layouts run the gamut from totally linear—just one path through—to bewilderingly labyrinthine. Dungeons have their own ecologies and are often dynamic. That is, those orcs don’t just lock themselves in a 20x20 room waiting for adventurers to wander in; they live there, they move around in it, they engage with other factions occupying the space.
Every DM knows how to run a dungeon. Something about it just makes sense: you go from room to room, you encounter obstacles and traps along the way, you interact with objects and NPCs, you fight monsters, you find treasure. You might even learn something about the history of the setting while you’re at it. It's a self-contained area where adventures happen.
It might be helpful to think about outdoor adventures the same way. When your players strike out into the wilderness, there’s no need to reinvent the game (a lesson I learned from constantly trying to reinvent the game). Just exchange your graph paper for hex paper.
Instead of drawing rooms and hallways, you’re drawing plains, hills, and forests separated by mountains, rivers, and canyons.
Instead of stocking rooms with furniture, artwork, chains on the walls, the vials and alembics of an alchemist, or barrels and chests, you're stocking outdoor areas with trees, plants, logs on the ground, stones, ruins, mile markers, road signs, abandoned wagons, and old campsites.
You still have monster and NPC encounters, just at longer distances. You can still find “secret doors” in the form of treasure hidden inside a tree or behind a stone in a wall or as previously unknown mountain passes and river fords. You may still be confronted by traps in the form of rickety rope bridges held up by worn-out ropes, rockslides, traps and snares set by hunters, or scree that can cause you to lose your footing and go tumbling down a hillside.
I’ve built entire campaigns by drawing a hex map, stocking each hex by rolling on random tables, and then building the backstory by drawing connections between whatever ends up in each hex. That’s a lot of planning up front, both in making the tables and in stocking each hex, but once you do it, you won’t have to prep again for a long time (unless the party makes a beeline for the uncharted corners of the map!). You could even save yourself the up-front prep and just roll on the random tables as the party enters each hex if you are confident in your improvisation skills. But many dungeon adventures involve exploring a specific, self-contained underground area; by the same token, your players could be tasked with exploring a specific 6 hex by 6 hex region of the map, whether to map the area, catalog plant species, prospect for precious metals, or drive off monsters.
When designing wilderness areas, whether it’s just to get the party from point A to point B or to create a wilderness adventure, set it up the same way you’d set up a dungeon. The game is Dungeons & Dragons, but you don’t have to take that phrase literally. Everything is a dungeon if you believe in your heart it is.
This might be met with "well, yeah, no kidding" by experienced DMs, but it's something that took me a long time to figure out on my own, so I hope it is helpful to people struggling with the same questions.