Ostufer is Ostufer, whatever the Arles call it. Same with anywhere that has been changed from one Arling to another. There's a reason Arlings take the name of their birth region - it's to remind their rulers where they come from, and who is their original base.
There are no ports quite like the ones of Ostufer. They almost don't even seem Thydian some times. And then you turn a corner, and you're hit with SomethingThatIsSuperThydianHere.
Many in Ostufer are fishers or sea-faring merchants. There are a few whaling towns, but Norrasjo holds a stronger hold on the whaling industry.
Eastern Ostufer is the wealthier side of the Arling, the side known for safer harbors.
Ostufer has many ruins from the Adrakian Empire's era, and small exploration expeditions have suggested parts of Ostufer had sunk into the sea as a result of rifts and ravines ripping across the landscape.
Most of the ruins are abandoned, though some are home to bandits or vagabonds.