Hexcrawl encounters can be, and often are, modeled after dungeon crawl encounters.
So for instance, Gary Gygax’s advice about how to randomly determine the contents of a room or chamber…
…can, with some tweaking, be applied to the contents of a hex map. Doing so means that over half the hexes in the map would be empty, and indeed this is what we tend to find in adventures such as Robert Conley’s Blackmarsh setting and John Stater’s Hexcrawl Classics Series. The table entries for “Monster” and “Monster and Treasure,” could also easily be adjusted to “Monster Lairs.” It might also include encounters with interesting NPCs, or encounters with creatures not found lairs, such as this entry from Blackmarsh:
0214 A mother black dragon (old, HD 8) and her child (young HD 7) have slaughtered a herd of dear and are in the meadow consuming their carcasses.
The “Special” table entry calls for a little more consideration. “Special and Stairway” might include items such as statues from a bygone age, interesting terrain features that might serve as landmarks for navigation, old battlefields, areas with strange arcane phenomena and other oddities.
The entry for tricks and traps can easily be amended to environmental hazards, puzzles, creatures with riddles etc. Likewise, the treasure entry for stocking dungeon chambers can similarly be co-opted.
What does not seem to fit as comfortably within the scheme of Gygax’s Table above are what to do with habitations such as villages, towns and cities as well as mines, dungeons, temples and monasteries. One could amend the original table to include a new category for these items or could try to shoehorn them into the “Monsters” or “Special” categories. Or one might combine Gygax’s method with Tom Moldvay’s advice for stocking the dungeon on pg. 52 of Basic:
Special monsters should be first placed in the appropriate rooms along with special treasures. The remaining rooms can be stocked as the DM wishes. If there is no preference to how the rooms are stocked, the following system may be used…
The “following system” turns out to be a table similar to Gygax’s. So adjusting this advice to hexcrawl stocking we might treat entries such as cities, dungeons and monasteries as “special” items to be placed first and use the table to randomly populate the rest.
Another mechanism that can easily be transferred from the dungeon to the wilderness is the wandering monster table. Just as each dungeon level and sublevel have their own tables so too each different environ can have its own table. And if you really wanted to keep the analogy tight you could design the environs to become more deadly the deeper into the wilderness the party travels.
I think this is a perfectly fine method for designing and stocking a wilderness hex map. Its symmetry with dungeoncrawl design certainly lends it the advantages of being streamlined and user friendly. Also, it’s much less demanding to stock only 40% of a map.
Attractive though this method is, some are quite happy to loosen up the analogy with dungeoncrawls and have offered sensible reasons for doing so. Justin Alexander is one of them. Allow me to quote at length a couple of the design goals which led him to introduce a system quite different from that of the dungeon crawl:
Third, the system is built around the assumption that every hex on the map will have at least one keyed location. And note that I said “location”, not encounter. Traditional hexcrawls will often included hexes keyed with encounters like this one (from the Wilderlands of Magic Realm):
A charismatic musician sits on a rock entertaining a group of Halfling children. He sings songs of high adventure and fighting Orcs.
While this system certainly could be used with such keys, my intention was to focus the key on content that could be used more than once as PCs visit and re-visit the same areas. (Particularly useful for an open gaming table.) In other words, the key is geography, not ephemera.
Fourth, to support all of these goals (hidden hexes, exploration, reusable material) I wanted to introduce uncertainty into whether or not the keyed content of a particular hex would be experienced (instead of automatically triggering the content when the hex was entered).
Alexander is not the only one who recommends stocking every hex with an encounter, Erin Smale over at Welsh Piper recommends doing the same. However as far as I can tell, Alexander’s design philosophy of keying only “location” encounters is idiosyncratic.
It does make sense though. In a dungeon all major elements of the physical environment have been mapped out. The party may pass through the same arched hallway and inner sanctum numerous times, and though they may encounter different creatures there periodically usually the structural elements of these locales remain the same, and soon become familiar. These structural elements lend character to a dungeon.
By contrast in a hexcrawl wilderness adventure where the hex size usually varies between 5-25 miles the only terrain features mapped out are regional environmental features (e.g. hills and forests) and any keyed material that happens to be part of the natural or built environment (e.g. towns and dungeons). Without many detailed “local” terrain features to differentiate the landscape, journeying through the wilderness can begin to feel a bit abstract and two dimensional. Creating keyed location encounters for each hex helps fill things out, adding a bit of personality to an otherwise bland and nebulous journey.
As for the other design goal regarding the uncertainty of finding these locations, this too makes a lot of sense. In addition to the reasons offered by Alexander, given the scale of each hex it would be odd if the party automatically discovered every keyed locale, no matter how concealed, whenever they entered a new hex.
These two design goals are not of course consistent with Gygax’s method for determining the content of a locale. There are no empty entries on Alexander’s model, and whatever monsters, treasure, tricks, traps and special encounters are encountered are encountered within the keyed locales (or via a random encounter table). Thus Alexander’s hexcrawl design ends up looking quite a bit different than that of a dungeoncrawl.
After considering both approaches when creating my Isles of Mist hexcrawl, I opted for Alexander’s method (for all the reasons just mentioned). However I still wanted the adventure to have some of those interesting monster and NPC encounters that Conley added in Blackmarsh and which Alexander attributes to the Wilderlands of Magic Realms. So instead of going for a traditional wandering monster encounter table, I decided to make each of the encounters on the table quite specific. For example, here’s the table I created for The Isle of the Dead:
One consequence of using unique table entries is that I’ll have to restock them more frequently. However I’m also more excited about using them at the table than I am other random encounter tables I’ve used in the past. At any rate this has all been very much a trial and error experiment in design for me. The real test will come when I playtest this adventure with my gaming group. Our next session is scheduled for this Saturday, so I’ll report back and let you know how it went later next week.
ars phantasia 
The way we used to play long ago was a variant on the first method. Just walking through the wilderness you would first roll for the chance for the encounter, then roll on the random encounter table if you got one(OD&D has a good one in Wilderness adventures, 1st edition Advanced D&D a passable one in the DMG, 2nd editions one is junk). However every time you walked through the hex you would have to roll for the chance of an encounter. If you wanted to clear the hex so that no more encounters would occur in the hex, then you would roll three times on the random encounter table and if you defeated all three encounters one right after the other the hex would cleared. Note that the hex would only remain cleared if you had a stronghold within 20 miles of it.
Interesting. I’ve not yet had the opportunity of playing the original version – in fact I’m just now exploring 1e and B/X. I planned on having encounter rolls made each time the party entered a hex. I like the idea of having rules for clearing a hex and setting up a stronghold though. Shows that I still have much to learn. Thanks for the feedback.