Tomb of Annihilation: Hex crawl procedure

As previously noted, the first half of Tomb of Annihilation largely consists of a hex crawl. This means that, outside of keyed hexes with static encounters, the game in this portion consists of procedurally-generated content. Do the adventurers get lost? Do they have enough supplies? Do they have any random encounters?

For my own needs, I assembled the following notes from the adventure book, the Player’s Handbook, and the Dungeon Master’s Guide. In a few places, the written guidance has some missing parts, so I filled in and noted accordingly. If you handle those parts differently, I’d love to see what you do!

UPDATE: My friend Juan pointed out where DMG page 111 provides more food and water on successful foraging than I realized.

UPDATE 2: Added more notes on Ranger and Wanderer. Merged water and food check step.

Jungles of Chult.jpg

Daily Procedure

  1. DM determines location on map.
  2. DM determines weather. Roll d20:(*)
    • 1-16: Occasional light rain: proceed as normal
    • 17-19: Heavy rain: Visibility limited to 150 feet
    • 20: Tropical storm: travel by canoe impossible, travel on foot gains 1 level of exhaustion, DC 10 Constitution save for another. Disadvantage on checks to avoid becoming lost
  3. Party determines navigator, pace, direction:
    • Normal pace: 2 hexes per day by canoe, 1 hex per day by foot. For rivers, upstream and downstream have no effect, and waterfalls occur every 10 to 20 miles (requiring portage of canoes).
    • Slow pace: 50% chance of 1 fewer hex per day, can hide from encounters or approach stealthily
    • Fast pace: 50% chance of 1 more hex per day, -5 to passive Perception
    • Parties with a Ranger are not slowed if in their favored terrain. Therefore(*), they gain the benefits of a slow pace without the chance of 1 fewer hex per day.
  4. DM rolls Wisdom (Survival) for Navigator:
    • DC 10 for coasts and lakes
    • DC 15 for jungles, mountains, rivers, swamps, and wastelands
    • Add to roll +5 for slow pace, -5 for fast pace
    • If lost, roll a d6 to determine which neighboring hex the party enters. Players are not shown their location on the map in this case.
    • Parties with a Ranger in their favored terrain cannot become lost in normal navigation.
  5. DM rolls d20 three times for random encounters (morning, afternoon, night). On a roll of 16 or higher, roll d100 and consult Appendix B based on terrain and, if in jungle, level of undead presence. Insert as appropriate during the travel sequence.
  6. Party checks for dehydration and malnourishment.
    • Characters can forage water if they succeed on a DC 10 Wisdom (Survival) check. A similar check can yield foraged food.
    • A successful forage yields (1d6 + Wisdom modifier) gallons of water or pounds of food, although each type of forage requires its own roll.
    • Foraging characters do not contribute to the group’s ability to notice threats.
    • Rangers in their favored terrain gather twice as much food and are able to notice threats while foraging.
    • Water from rivers and lakes should be boiled first.
    • Raincatchers (ToA p. 32) can catch 2 gallons of water per inch of rain and hold up to 8 gallons.
    • On heavy rain days, roll d4 for inches of rain. On storm days, assume full 4 inches or more.(*)
    • Characters with <2 gallons of water must make DC 15 Constitution saving throw or gain 1 level of exhaustion (disadvantage if wearing heavy clothing or medium or heavy armor). Traveling at a fast pace adds -5 penalty to this saving throw. (According to the PHB, if the character already has one or more levels of exhaustion, the character takes two levels.)
    • Characters with the Wanderer background feature (typically Outlanders) can automatically find food and fresh water for themselves and up to five other people each day in suitable terrain.
    • Expend 1 unit of rations (1 pound of food).
    • Each day after (3 plus Constitution modifier) days without food, a character gains 1 level of exhaustion. A normal day of eating resets this counter to 0.

(*): These steps are not found in the published game materials and may be altered at DM’s discretion.

Exhaustion effects

Level Effect
1 Disadvantage on ability checks
2 Speed halved
3 Disadvantage on attack rolls and saving throws
4 Hit point maximum halved
5 Speed reduced to 0
6 Death

34 thoughts on “Tomb of Annihilation: Hex crawl procedure

    1. Honestly, we used the travel and hex-generation rules from Source of the Nile and it worked far better than what ToA suggested.


  1. Hi. I love this and will definitely refer to it in my campaign. One comment on these lines about the Ranger: “Parties with a Ranger are not slowed by the terrain,” and “Parties with a Ranger cannot become lost in normal navigation.” It is possible I missed an exception to the normal rule in Tomb of Annihilation, but per the PHB, these circumstances apply only when traveling in a Ranger’s favored terrain (as you noted in the foraging section). It might be worth mentioning on those lines.

    Thank you so much for putting this together!


  2. If you allow the Unearthed Arcana revised version of the Ranger that WotC put out, rather than Favored Terrain, they have this.
    Natural Explorer
    You are a master of navigating the natural world, and you react with swift and decisive action when attacked. This grants you the following benefits:
    • You ignore difficult terrain.
    • You have advantage on initiative rolls.
    • On your first turn during combat, you have advantage on attack rolls against creatures that have not yet acted.

    In addition, you are skilled at navigating the wilderness.
    You gain the following benefits when traveling for an hour or more:
    • Difficult terrain doesn’t slow your group’s travel.
    • Your group can’t become lost except by magical means.
    • Even when you are engaged in another activity while traveling (such as foraging, navigating, or tracking), you remain alert to danger.
    • If you are traveling alone, you can move stealthily at a normal pace.
    • When you forage, you find twice as much food as you normally would.
    • While tracking other creatures, you also learn their exact number, their sizes, and how long ago they passed through the area.

    Which you might think takes away some of the inherent challenge of the exploration and jungle survival aspects of the campaign and might want to adjust accordingly.


    1. We are also using the unearthed arcana ranger and decided that not getting lost at all wasn’t something we liked. So we went with the idea that fast movement created the same chance of getting lost as if the party was travelling at normal speed. It doesn’t happen often (getting lost) but when they did get lost and stumbled into Camp Righteous, they got the treasure and then rocks fell and everybody died.


  3. I am having a tough time finding a map key for the various types of terrains. I think I’ve figured out desert and wasteland, but which green is swamps and which is jungle?


    1. I also regretted the lack of a terrain key. But the swamps seem to be the lighter green around the lakes rather than the dark green trees of the jungle covering most of the peninsula.


  4. Do we really need a hex? Couldnt we do the traveling just by measuring miles etc? What do the hexes add?


  5. This is great! One thing I would note is that Purify Food and Drink can make contaminated river water into potable fresh water, so while traveling along rivers this ritual makes foraging for water a lot easier.


  6. Slow movement on foot seems very punishing. Party not moving at all 50% of the time is a bit of a time-sink with not a lot of fun.


      1. I think you misunderstood: “Normal pace: 2 hexes per day by canoe, 1 hex per day by foot.” So 2 hex is only default in a canoe.


    1. Would it be possible to add a temperature generator to this program? That would make it absolutely perfect!


  7. Hi. I liked a lot but it can be better. You should keep the official rules about weather (DMG page 109). Temperature is important because if the weather is colder than normal, than means that the water needs are halved (1 gallon per day instead of 2 gallons per day).


  8. This is really good work. I copied it so that I can have it by my side when the part is in the jungle. Its a good “To do list to check everyday.


  9. Hi,
    Can you authorize me to translate your hexcrawl notes into French?
    (including as a reference a link to your webpage)
    Thank you


  10. Or you could use the terrain generation rules from Source of the Nile, it’s basically the same system EGG used as he was a long time wargamer too.

    Click to access sotnrules.pdf

    (section 10 is mapping new hexes; yes, crazy detailed river rules)


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