It seems there is nothing more to learn at that place.

You should visit the frost giant's castle and see if you can find any information on the death of the horkers. Enter through the underwater caves to the north of the castle.

It is a castle made of ice on the northwest part of Solstheim. There lives the frost giant Karstaag. The Skaal have lived in peace with the monster for many years, but we have heard nothing from the giant for some time. This slaughter could be the workings of the Rieklings who serve him. Go there and find out what you can. You will not be allowed in the main entrance, but we have recently discovered an entrance in the waters north of the castle. Good luck to you, Blodskaal.

I have met the master of that place, though I hope never to meet him again.

I've never heard of it. There have been rumors about some giant ice castle to the north, but I don't believe them.

It is the lair of the frost giant Karstaag. The Skaal hold an uneasy truce with this monster.

To the far north is a great castle of ice. Is this the place you speak of?