According to Duke Darcy, the second strata is a marshland environment. It is full of swamps and rivers that would make the place annoying if one is ill-equipped from exploring the place. The reason they have taken time to reach the next strata was because of the environment itself. One wrong move and the marshlands might end up trapping someone alive. As for the monsters, typical marshland monsters appears to terrorize the place. The most common enemies are mutated fishmen and mud golems. They are pretty easy to deal with according to Duke Darcy, but they became troublesome and dangerous the moment they start to swarm.