I would like to go to Banda Aceh from Phuket (Thailand) in early December, but the flight is very complicated and expensive...
Is there another way to get Banda Aceh? (boat/ferry, back of the little mermaid.. )
You can, but it is a very roundabout solution. From Phuket, you must travel to Singapore. From there you can take the Ferry to the port of Belawan. Then travel to Banda Aceh. Another route is from Pulau Aceh which travels to MIN Ulee Lheue. Unfortunately according to here, Banda Aceh travel, the ferry from Penang was closed.
The ferry from Penang is no longer operating.
One thing I did notice, have you thought about flying out of Penang? It seems flights are much cheaper.
SIDENOTE: If you fly from Phuket to Kuala Lumpur in early Dec. the rates are much cheaper. Then fly from Kuala Lumpur to Banda Aceh. But I can see why you mentioned this is complicated.
ADDENDUM: However, I looked up flights in Air Asia matching early Dec flights. My trip went from Phuket to Kuala Lumpur, then Kuala Lumpur to Banda Aceh.
Total Price: $171.81 or 5950.38 Thai Baht