All the 300 students of the gold section were standing in front of a medium-sized fortress, which was 3 stories tall in terms of height, and a reinforced Iron gate was at its front, which was unbreakable beneath the power of anyone below the late 2nd phase Seeker. The walls are also very thick and robust, pretty much unbreakable even by the strongest one among them.
You can't break down the iron door or the walls in any way, and the walls are high enough that you can't jump through on that. Well, even if you could, there would be a large number of enemies on the walls or shooters there, and that's a recipe to get killed.
Not only that, surrounding the fortress itself is a circular waterway, and there are some dangerous 2nd tier water beasts in high numbers, so dropping into the water is also a bad idea.
