As a side question to mdrichey's post PHB Ranger Natural Explorer: Does Underdark terrain type mean any underground terrain? I would like to get a bit more clarification:

If my character was raised in a dwarven village, within the caves inside a mountain, would his Natural Explorer feature not reflect this, giving him proficiency in caves and dungeon passages?

For clarification to keep it RAW: Would caves/dungeons be classified under the Mountain terrain type? If not, which favored terrain type would they fall under, if any?

I know that dungeons are not always holes in the ground, but for the times they are, I am asking if it would count?


1 Answer 1


It depends on the dungeon / cave, and if your DM thinks it applies

The first Natural Explorer condition is pretty vague:

When you make an Intelligence or Wisdom check related to your favored terrain, your proficiency bonus is doubled if you are using a skill that you’re proficient in.

The second condition is a little less vague:

While traveling for an hour or more in your favored terrain, you gain the following benefits:

So, for the first condition, what you are doing inside the terrain must be related to it. So, if you are inside of a cave/dungeon, and experience from your natural terrain directly applies to the check you are making, the double proficiency applies to it. For instance, say you are inside of a cave, and you find some minerals. Even if your DM does not classify this as in your favoured terrain, and your DM thinks that your knowledge of minerals applies, it could help you identify these minerals if the skill check is something you are proficient in. This ability is purely based on relation to your terrain, so a DM could rule that your experience in mountains qualifies for caves if they think it does, but if they don't, you don't get double proficiency.

For the second one, it states that you need to have traveled in your terrain for an hour or more. This means that the benefits apply if you have been travelling for at least an hour and if you are in of the terrain. So, if you are in a cave/dungeon in a mountainous terrain (and you have been travelling for at least an hour), these abilities apply. If the cave/dungeon is in a different terrain (as determined by your DM), they do not apply.

If a dungeon/cave is 'in the mountains', whether it is mountains at the other side of the world, or what you are familiar with, it RAW qualifies as mountainous terrain, so it qualifies. If it is 'a vast subterranean realm inhabited by drow, mindflayers, aboleth, and other strange, sinister creatures' (definition from Wikipedia), it is underdark, etc.

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    \$\begingroup\$ I understand what you're saying, and thank you for your answer. One clarification that I would like is where similarities occur. For instance, people who do spelunking will notice oddities even if they go to caves on the other side of the world, because the natural processes or artificial creation of tunneling will leave common facts regardless if you are going through rocks or dirt... So in that case, would it grant proficiencies in understanding how to navigate maze-like tunnels while traveling dungeons? (Note: This idea actually happened in a campaign, killing the party) \$\endgroup\$
    – Victor B
    Mar 6, 2019 at 1:10
  • \$\begingroup\$ @VictorB I added these as examples, and edited the heading to try and address your issue \$\endgroup\$
    – Juicetin
    Mar 6, 2019 at 1:26

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