Can you move while Hidden?

Question

Assuming you have successfully Hidden, can you:

1. Continue to be not 'clearly visible' while moving and remain Hidden?
2. Become 'clearly visible' while moving and remain Hidden?

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In the description of the Stealth skill, it says:

Make a Dexterity (Stealth) check when you attempt to conceal yourself from enemies, slink past guards, slip away without being noticed, or sneak up on someone without being seen or heard.

So you can definitely move unseen with a Stealth action, but is that allowed in the Hide action?

The sidebar on "Hiding" states:

Until you are discovered or you stop hiding, that check's total is contested by the Wisdom (Perception) check of any creature that actively searches for signs of your presence.

[...]

You can't hide from a creature that can see you clearly, and you give away your position if you make noise, such as shouting a warning or knocking over a vase.

[...]

Passive Perception. When you hide, there's a chance someone will notice you even if they aren't searching. To determine whether such a creature notices you, the DM compares your Dexterity (Stealth) check with that creature's passive Wisdom (Perception) score, [...]

The rules clearly state that in order to hide you only need to be 'not clearly seen' and it is successful if you beat the opponent's Passive Perception. Your position is given away if you make noise (although you are not revealed). If an opponent takes the Search action to make a Perception check and beats your Stealth roll then you are discovered.

So the Hide action is a Stealth roll contested by Passive Perception. Creatures can contest the roll with the Search action using their Perception. Unless a creature opts to no longer be hidden, this is the only ways they can be revealed?

This seems to indicate that moving has no bearing on remaining hidden.

Answer 1

Can you continue to be not 'clearly visible' while moving and remain Hidden?

Yes, unless you are travelling for long distances at a normal or fast pace.

Can you become 'clearly visible' while moving and remain Hidden?

Yes, if the circumstance allows it, but usually not when you approach someone in combat.

Movement matters for hiding in two general cases

When you move over a distance measured in days, hours, or miles, this paragraph in Activity while Traveling applies:

While traveling at a slow pace, the characters can move stealthily. As long as they're not in the open, they can try to surprise or sneak by other creatures they encounter. See the rules for hiding in chapter 7.

While you are in combat, this paragraph of the Hiding sidebar applies:

In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you. However, under certain circumstances, the Dungeon Master might allow you to stay hidden as you approach a creature that is distracted, allowing you to gain advantage on an attack before you are seen.

There are also a handful of specific features and traits which tie movement and stealth together to varying degrees, such as the Ranger's Hide in Plain Sight feature or the Gargoyle's False Appearance trait.

You can't be both clearly seen and hidden from a creature

The Hiding sidebar states:

You can't hide from a creature that can see you clearly, and if you make noise (such as shouting a warning or knocking over a vase), you give away your position.

This applies throughout the whole time your are hidden, not just the moment when you begin to hide. Moreover, the sidebar states:

Ultimately, the DM decides when circumstances are appropriate for hiding.

Which implies a change in circumstances can cause you to become unhidden. This is consistent with the Ability Checks chapter, which states:

An ability check tests a character's or monster's innate talent and training in an effort to overcome a challenge. The DM calls for an ability check when a character or monster attempts an action (other than an attack) that has a chance of failure. When the outcome is uncertain, the dice determine the results.

If the outcome is certain, then dice do not determine the result. If the circumstance changes such that you are clearly seen, then by definition the outcome of hiding is certain failure and the stealth check no longer determines the outcome.

That said, whether being clearly visible means you are clearly seen depends on the circumstances. For instance, if you are out in the open and approaching a sleeping creature, you are clearly visible, but it's uncertain whether that creature wakes up and sees you, so the stealth check determines the outcome.

Answer 2

It depends on circumstances

If you aren't in combat and the enemy has reason to suspect you are around, then it is your Stealth vs. their passive Perception as long as you are keeping out of sight. If you move openly in front of the enemy, then they will see you.

If you aren't in combat and they have reason to suspect you are hiding nearby, they can make active search checks vs. your Stealth roll. Again, this does require you to have somewhere you can hide. If you hide behind a giant vase and an enemy looks behind that vase, you can't expect to be undetected. It can some down to roleplaying in that case. A guard might search in the obvious locations but not find you if you've found a good place to hide.

If you are in combat, you can generally only move around while staying hidden if you can keep out of the line of sight of your enemy or enemies. From another part of the Hiding sidebar:

In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you. However, under certain circumstances, the GM might allow you to stay hidden as you approach a creature that is distracted, allowing you to gain advantage on an attack roll before you are seen.

Your DM might allow you to sneak up on an enemy if you can justify it somehow, e.g. crawling through long grass or having an ally keeping your opponents distracted.

Note of course that magic can alter this. If you are invisible, and your enemy has no means of seeing past it, then keeping out of line of sight isn't required. If you are in the field of a silence spell, then doing things that would normally make noise doesn't matter.

Trying to stealth around creatures that can track by scent is a different prospect altogether. Aside from stinking cloud, I'm not sure how you'd counter that.

If you attack in combat while hidden then you're location will be known afterwards:

If you are hidden—both unseen and unheard—when you make an attack, you give away your location when the attack hits or misses.

You might still be hidden afterwards if there are conditions in place that stop you being both seen and heard. But your enemy will still have a fix on the location you were at when you attacked.