There are 3 paths.
Through the forest – where snipers are stationed, and you can advance by gaining +1 level on the trees. Exit to the elven forest from the south and proceed further.
Through the dungeons in 2 turns. The first path leads directly north and involves crossing a water barrier by summoning a ship (there is a water spell near the first town).
Or, go west through the anti-magic guard; there will be an exit to the surface, again near the elven town.