bold of you to assume I have a doormat
It is up your anus
Oh, hyperspace~ 
naughty naughty
I am going to now have an absolutely awful time on the toilet.
Bros gut bacteria are going mental 
(deleted)
I cannot imagine the horror contained within that message before it was deleted
Assuming that they have access to either modern weaponry, in-game items, or can simply attain in-game powers, they should be able to take on the waves of the dark seas, take down all of the atlanteans up to the far reaches, and constantly obtain new supplies from chests and resources found on islands.
On the chance that they have access to modern weaponry:
The only danger that they would be facing would be plasma and lightning based disasters alongside tornadoes.
Any enemy would be instantly felled by guns and explosives while the likes of disease and insanity could be reduced through medicine. Given enough time, you could even expect them to figure out a way to completely negate the effect the dark sea has over people by studying what causes them and what stops them.
On the chance that they have access to in-game items:
Through ship attachments, weaponry, and potions, they should be able to go against everything.
Yeah, I’m getting lazy, how could you tell?
On the chance that they have access to in-game powers:
They could perpetually train each others, level up their powers, and essentially become immortal mages.
Yeah, I gave up on this, how could you tell?
I was gonna put it in Quotables before I realized I don’t know how to do that
in this situation they cannot gain in-game powers they are just normal humans from the real world (don’t ask how they got into the AO world just deal with it)
The entire British navy got hit by a truck and got isekaid