Don't be a baby, go there and show them what's what. And if you can't manage at first, gain a few levels and try again, it's great fun. Not all skull icons are the same level, some can go as high as level 30. And nope, it won't disappear until you claim the treasure there.

Think of it like a boss-battle, and be sure to prepare first, with oils and potions etc. It's such fun.

theres an archgriffin on an islsnd in skellige and i think its lvl46, its kicked my arse a few times now (im lvl36), i dont think skull icons mean its unbeatable but it will be a tough fight.

Thanks... the truth is I am advancing slowly since I love exploring the places by simply roaming around... Scouting the areas to see where the most dangerous areas are... and of course... admiring the view!!! hehe...I think I will level up until level 12 or sth and then I am going to show them who's the boss...

A skull icon simply means that the monster is a high level compared to you. As you level up, the monster's icon will go from skull to red to green, and finally to grey.

The red skull shows up as an indication that there is a huge difference between your character level and the level of the monster as a way to inform and deter you from attempting to fight it right away. When you gain enough levels to be stronger and more capable to handle a fight with the monster, the red skull will disappear. The skull is just a "DANGER DANGER" warning to you, nothing more.

You'll have to find your own comfort zone as to how comfortable you are fighting higher level enemies and be careful the higher the spread. Your skill will improve over time likely too, affording you greater leeway in fighting higher level monsters. I'm pretty comfortable fighting 4-5 level higher creatures for the most part, and maybe the occasional even slightly higher, but not near the start of the game, just in the middle. Also certain enemies are tough enough that it is a good idea to wait it out and come back when you're level matched.

Then there's that level 48 archgrifin mikbhoy alluded to. I'm level 35 and he kicked my arse too although I watched a video on youtube of someone killing him at level 36 using only Quen and Igni, exploding arrows, and dodge and roll. Took him about 5 minutes so I'll have to try that again.

Thanks everyone for the tips... Every bit of info is very helpful!!

There is other posibilites. Skull only mean difference in levels.

Very easy kill big spider because it attak with poison and superior golden oriole made me invincible to it.
Very easy won fistfight with "skull" only because counterattack.
Easy kill griffin in mountains because i was standing on a narrow eave where griffin can't land and shoot from arbalet. Then drop half dead beast on eaves to me. He can't normally fight in narrow space and got just sloughtered.