I suspect that Silversea is looking to grow the fly in / fly out market and this hotel is critical to that. Flying to Antarctica will always be a bit iffy as weather can disrupt plans at a moment's notice. Now Silversea will have better control over its passengers in the event of those disruptions.
It's interesting that there is a concept of northernmost and southernmost while it would be nonsensical to talk of easternmost or westernmost, yet the earth is a sphere in all directions!
This is a bit of a throwback to the destination hotels that railroad companies used to build.
My Drake crossing was 2-5 meters. Problem with flights is weather conditions need to be close to perfect. Unpleasant, you can still cross in 8-10-meter waves.
I suppose it depends on your definition of "hotel," but there's a strong argument that White Desert owns the southernmost title...
I think the biggest benefit of this and having everything done via Silvesea is the flexibility it adds in case of inclement weather. Not having to worry about your accommodations and plans if flights get cancelled (sometimes for days) is a huge value add. Smart move by them.
