ToME: the Tales of Maj'Eyal

I installed the game yesterday (amazed with it) and I cleared the first level of the Maze and there are no stairs to go down. But on the right edge of the floor there is a closed off room that is surrounded by tall walls which probably has the stairs. I swapped an infusion to blink and I've tried digging. I'm playing the melee sword/shield tanky char.

Are there huge, black holes in the floor? If so, you're in the so-called "alt" maze and need to jump (just move as normal) into them.

That's it! Thanks!