He opens it and looks inside.

While Xaul and Skye are slinging shit, Damros will move closer to the walls and attempt to move up the 'northern' sewer branch to see if any more 'sunburst' images are on the walls.   If none appear within 50 feet of the junction, he will move 'south' to check the walls along the southern branch.

{game log} STEALTH:  16   (13+3)         PERCEPTION:  6  (2+4)

You do see a symbol on both branches. But also one on the door. As for the other side of the door.... I'll get to that tomorrow once I can get the map for it 

In fact, a map isn't needed (with the time it takes to get one sorted, I will wait until you get a little further). The other side of that door is a short corridor going 15ft north, with another arrow slit in it at the end (based on the location, probably from the same room as the one just to the north of the door) and another door at the end on the left of the corridor. 

Xaul exits the corridor and tells the party about what he’s found. ‘Since there are those symbols on all three routes, I say we take this one through the corridor since that at least means we won’t be trudging through sewage’ He then goes back inside, and casts mage hand to rattle the handle of the next door. Seeing it’s unlocked, he then opens it with caution and heads through. 

Skye follows Xual, holding her breath. 

Sehaethas also links the idea of getting out of the sewage. Once out of the sewer, he asks Kylaski, "Can you clean us up?"

(sorry, had a surprise, wifi-less holiday)

There is a T-junction. Heading left is a small room. Rusty weapons and threadbare clothing litter the floor of this area, which serves as a coat room and armoury. It contains nothing of value. Heading right has a small room with the arrow slits out which has one sleeping goblin in it, who looks like it was supposed to be on lookout. You somehow have not woken it up yet, but probably hitting it with sewer water would have woken it. (map update tomorrow)

Damros moves back and grabs a piece of old clothing before sliding up next to Xaul and whispering, "If you can sit on him, I will stuff a rag in his mouth. Then we can tie him up."

Xaul looks at Damros, his mouth slightly agape, and then just shrugs and whispers 'Sure, why not, after all we've done so far, why wouldn't I just sit on a sleeping goblin why you gag them?' He walks over to the poor, sleeping goblin, looks at him for a second to try and best work out how to do this, then just plumps himself down onto the creature. As Damros comes over to gag the now-awakened goblin, he hisses in his ear 'You owe me so many drinks when we get back to the Yawning Portal'. Athletics check to...um...position his weight to stop the goblin wriggling free? I don't even know anymore man: 13

Well then.... You know what.... Sure. You now have one traumatised and gagged goblin. (though as of yet untied. Anyone got rope?) 

Damros has manacles as well as rope available in his backpack.   (( don't ask... ))

While shoving the rags in the goblin's mouth, Damros will ask someone to dig out the rope and begin tying the goblin securely.

Sehaethas will take the rope attacked to Damros' backpack and start tying up the goblin. Sehaethas doesn't have rope of his own.

Skye nods encouragingly, ready for the interrogation. 

If the goblin is securely tied up, Xaul will get back up and apologise, even if he's the enemy.

You have enough people there and aren't under any particular time pressure. Especially as the goblin isn't putting up much fight being sat on and utterly surrounded. So you can get a secure tying up without a check. 

(overdue map update as I forgot I didn't do it)

Once the goblin is securely tied, Sehaethas will sit back and let the others do the questioning. 

OOC: Sehaethas has low chr for a warlock...

Xaul isn't in the mood for interrogation, especially after their bizarre method of restraining the goblin in the first place. He looks to Damros and says 'You can do the honours, I don't think I've got the level of...uh...edge against him that this interrogation needs anymore.'

Intimidation (nat20+3). 

Skye squats down near the goblins head, leaning to face it eye to eye. She jerks her head at Xual. “My friend, he ain’t always so friendly. He listens to me, sometimes. And if I tell him you’re useful… well. I think we’ll all be happy if you can give me a reason to tell him that you’re being useful and you’ll continue to be useful. Understand?” 

Damros comes over and squats beside Skye and the goblin.     {game log}  Persuasion:  14+5 = 19

"Now, my friend... here is the situation.   We COULD have killed you while you were napping BUT, we did not.  Instead we did the polite thing and just tied you up so we could speak with you.  Ask a few questions and maybe be on our way. "
 
Damros reaches out to remove the cloth gag.
 
"On your honor, I expect you to NOT yell or scream when I remove this gag.  If you DO yell, scream, or other wise attempt to raise an alarm... not only will I have to gag you again but, we will have to decide if you live or die.   Choose life, my friend."

Damros will slowly remove the gag... prepared to insert it again if the goblin chooses unwisely.