no water at all. there is no water at that depth..
are you sure more light would fix it? a long time ago, slimes were completely immune from the effects of light. might be worth a try, I have plenty of coal to make more torches. but my tunnels are rather long...
by the way, bronze pickaxes are great! all the benefits of iron pickaxes, can mine all new materials at great speed, and unlike iron, the materials used to craft it are extremely common! more common than coal, in fact. I could make a full chest of them, and I would be able to get back the copper and tin used just by mining the veins that are on my tunnel walls and I just ignored. Finally an use for all that ore!
a question: do water mills work with running water? I saw a video in which they seemed to be able to do so.
If they can work in that way, I got an idea for a rather large water turbine... I just need to understand what effect do surrounding blocks have on them. if it works, all I need is a sea, an incredible big room and unbelievable quantities of iron. Hopefully, the experimental generator will make enough power for the automatic miners to give me all the iron I need.
edit: i believe vertical axis is y. and if I moved up, I would not find diamonds... I think I'll deal with slimes. they are not dangerous anyway.