Swallowed creatures are considered Unseen Attackers. Yes or No?

Something that came up a while ago during a campaign with a particularly hostile DM I used to have: one player had been swallowed by another creature, which gave them Total Cover against the outside, as well as the Restrained and Blinded condition, which meant they had disadvantage on their attacks against the creature that had swallowed them.

I argued that because they were inside their stomach, the creature couldn't possibly see them, and therefore the swallowed player had advantage from being an Unseen Attacker, which the DM refused to acknowledge. The DM does whatever they want within their games, but by the rules, they should have had advantage, right?

Ignoring the biological effects of being inside a creature, there is no freedom of movement for the attacker.  Disadvantage make sense as they do not have the space to swing a weapon, they can basically just stab with out the use of leverage to get a good swing in.  Bludgeon damage type weapons would not work very well either.

Basically the swallowed rules are pretty basic and not realistic. But then, the idea that a monster would swallow a creature that is still alive is also not very realistic - insides are generally very squishy & vulnerable, so creatures should not want to swallow anything that could move in there and potentially hurt them.

Realistic swallowing rules would be something like:

- Melee attacks automatically hit, bludgeoning weapons deal no damage, slashing weapons do half damage, and piercing weapons do full damage.
- Ranged attacks are at disadvantage.
- The swallowed creature cannot breath, casting spells with V component or talking cause the creature to start suffocating.
- At the end of each turn the swallowed creature must make a DC 15 Strength saving throw or drop the weapon it is holding as the internal musculature pushes the creature deeper into the monster. If the creature is holding a Light weapon they have Advantage on this save.

I think there's a misunderstanding. I meant that being an Unseen Attacker should be considered a source of advantage. Being Blinded and Restrained still gives disadvantage, so attacks should be straight rolls, but not with disadvantage.

Quote from Natrel >>

Something that came up a while ago during a campaign with a particularly hostile DM I used to have: one player had been swallowed by another creature, which gave them Total Cover against the outside, as well as the Restrained and Blinded condition, which meant they had disadvantage on their attacks against the creature that had swallowed them.

I argued that because they were inside their stomach, the creature couldn't possibly see them, and therefore the swallowed player had advantage from being an Unseen Attacker, which the DM refused to acknowledge. The DM does whatever they want within their games, but by the rules, they should have had advantage, right?

 While I see the reasoning, no. Your DM is correct.

I could make an argument to justify it within the abstract rule framework, but I'm not going to try. This is an exceptional condition. You have disadvantage to represent the difficulty of attacking at all. If you had advantage from being unseen, which you always would be under the circumstances, then it could be mentioned in the rules about being swallowed. It's not, so you don't.

I mean, I think you could rule it that they are unseen and thus should get advantage RAW, but I don't think that is a forgone conclusion.

Bringing some logic into this (dangerous when we're talking about D&D rules, I know), the rules for Unseen Attacker represent the inability of a target to prepare for/react to an attack because they cannot see the source of the attack. Harder to dodge an arrow flying at you when you have no idea what direction it is coming from.

However, this would not be true from within a creature. The creature knows you are there (it swallowed you). There's no real advantage from Unseen Attacker because they do know where you are. I've seen others suggest before that creatures should have Blindsight to things within them (specifically creatures who can swallow would still be RAW depicted as being able to perceive your presence), and I agree with that. Because there are no "vulnerability" rules for when you are swallowed by a creature (i.e. "The Froghemouth is vulnerable to piercing and slashing damage from creatures within its stomach") we can assume the outside is just as tough and difficult to pierce as the inside. Otherwise the creature probably wouldn't be swallowing fully armored adventurers. 

Is it a bit silly? Yeah. It makes it hard to play out that power fantasy of diving down the gullet of a massive creature and then slashing its insides for massive damage. But I think we can use Drax in Guardians of the Galaxy Vol 2. going inside the Abilisk as an example. He dives in thinking he can do more damage from the inside, because he cannot pierce its hide from the outside. He turns out to be incorrect. 

So while you are DMing, if you ruled the creature inside another would be unseen and thus make straight roles would be fine, your DM didn't do anything wrong with the way they ruled.