How to go up there? Its simply impossible

Er... go up where?

If it's a dragon roost or something on top of a mountain and you can't climb it, there may be a cave or tunnel that leads up to it. Or the climb might be on the other side of the mountain. If a quest is pointing to it, try the clairvoyance spell to find the route.

http://steamcommunity.com/sharedfiles/filedetails/?id=12185939

Wow, that's an old picture.

The "Hidden" Peaks on Solsthiem can all be reached by foot.

There's a mod called Airstream Levitation -- http://steamcommunity.com/sharedfiles/filedetails/?id=16073&searchtext=Airstream+Levitation -- that allows you to move to places that you can't climb to. HOWEVER, you will find the edges of the playing area (East, West, North, South, AND vertically) when the "You can't go that way" message pops up. Pointedly, you can see what lies beyond the limits of movement, all the way to a distant horizon or up to a lofty peak. That's just good graphics; it beats having a featureless fog one inch beyond where you _can_ move to.

I've heard of command line options on the PC that let you fly around or go through walls/floors. Perhaps someone who is on that platform can comment.

For the console, the best option is to get a horse. Horses can climb ridiculous slopes, but be careful when you're coming back down. A fall can kill both you and your horse.

Even better, there's a long standing bug in the engine that's existed since Oblivion that let's you scale almost any near vertical slope. Not sure if it's known online or not, so if it is you'll probably be able to find it. I think I'll hold out till the next game made with this engine before explaining it if it's not already known, don't want them to patch out my mountain climbing!

Is that with or without horses?

I often find that most slopes can be climbed if you explore enough and have patience. It can involve a lot of jumping.

This, it's a pain to do but it's possible.
The other way is to summon Arvak as there's no horses on the island.

Yeah, I noticed Shadowmere didn't come across with my PC. Fortunately, I did the Dawnguard quests and got Arvak.

"tcl" toggles clipping. In other words you can move trough everything and gravity doesn't have an effect.

I am unsure what peak you mean but I recommend going up on horseback, just jump over rocks and watch him hover up any mountain side.
I would also suggest using arvak as this method can be perilous as 1 or 2...or 10 horses have previously found out

lol, i thought you mistyped and meant "perks" and i was all set to start yappin about how skill levels should have auto-upgrades like oblivion and not be tied to perks and there would be more customization and on..