How is that possible!? To reach the Minotaur, you need to see that shore (in order to cross it with boots of levitation), and for that, you need expert scouting and two pipes, one of which is in the northwest of the dungeon.
You're mistaken. You need expert scouting and 1 pipe, which I took from a defeated hero. And the northeastern squares (which need to be revealed to fly over with boots of levitation) can be revealed from the water :) when you swim there, if you swim close to the shore (more precisely, to the rocks in the water).