To successfully and quickly discover Carlin area you require: Luck or time & patience.
I believe the Ice Island you trying to get is Artic Faun's Island1. Unfortunately, it is random event to get there, similarly to the Ghost Ship when you travel from Venore to Darashia. Therefore you will have to try, until you get there. Once you are there, you will have cool-down of 20 hrs to get there again. To get there you have to go to Port Hope, Speak with NPC Charles
You will have to write to him
"Hi
Shortcut
Yes
Liberty Bay
Yes"
And then from Liberty Bay back to Port Hope again, if not successfully. Liberty Bay will cost you only 50 GP, so try to stick to this one:-)
You will have to repeat this message until you lucky and end up on the Island. For some it takes few minutes, for others days....
Found also some video tutorial (Portuguese only)- https://www.youtube.com/watch?v=xZ96RLM2-9k
1. https://tibia.fandom.com/wiki/Arctic_Faun%27s_Island