It would really depend on how bright it needs to be. What's gonna be done in this cave?

But lets say for just a general light that would give plenty to see by (but wouldn't be enough for detailed work or anything) .. a strip of 12 1xF96T8 slimlines right down the center (that wouldn't even be a 10th of your 8kw .LOL. ) Maybe 2 strips of 12 2x96T8 along the length of it would be better.

Or if really wanted to light it up.. 2 strips of 25 2xF54T5 HO's along the length of it! 100 of those lamps would be more than enough light :cool:

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Or  maybe its gonna be a party/club cave...fill the 'ceiling' with a bunch of Disco Balls, DJ lights, Blacklights, and colored fluorescents(all dimmable ofcourse) full DMX/computer control of it all.

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Or for a nice starry-night/festive look... string up a bunch of LED twinkle Christmas lights to cover the 'ceiling' (this would be the toughest one since they don't sell them & you'd need to "make" your own, saying 25-foot per set, and spaced 1-foot apart, that's like 84 sets). A few hundred watts total, you'd have plenty of power to spare .LOL.

I would have 4 rows of 25 2xF40T12 industrials.

You need to light a 100 ft. long by 20 ft. high by 10ft. wide cave. You have 8000 watts of power available. What lighting technology do you use?
Anything goes! I want to see your clever ideas!     

I would use a couple of 1650 watt metal halide lamps!!!!!