Ouch, the ground opened, and took my character from town to the 10th depth.
Well, let's say that level 8 dwarf warrior wasn't really ready for that, both in term of equipment and in term of hope, so i was ready to use my town recall scroll.
Tough i noticed a pile of gold nearby, ran to it (as depth 10 money = lots of money) i ran straight into an acid trap.
And guess what the acid trap did : yeah it destroyed my only town recall scroll ... fantastic ...
Oh well, it would be a long long climbing up and he would probably die anyways at that point.
But he survived ! and managed to get back to town despite how huge every depth was and how apparently ridiculously rare stairs leading up were (i wonder if the dev has been vicious enough to only have 1 of them spawn by depth, unlike stairs leading down that are nearly everywhere) that took so insanely long to find.
On the way up level 8 dwarf warrior got a huge truckload of additional kills and vast amount of money (as the lower depth you are the more money you'll find both on ground or tunnelling into precious tiles), so much that he managed to kill Smeagol, Wormtongue and with a lot more difficulty Mugash the kobold lord and Brodda the easterling (yeah for berserk potion and cure serious wounds i had)
I didn't had to clear all depths , but i did because those upstairs were so rare that i had to explore those giants levels and so kill nearly everything on the way.
At least this nasty experience really helped to equip my character and power him up a bit.
Oh and in this long climbing back, i found 0 town recall scroll, so if you play the game, better buy a couple more of them in town before doing something stupid like reading a scroll of descent with a low level character