"Pat Keith" writes:
Whats the best way to drill thru a boulder?

depends on the composition of the boulder.
anything from a star chisel to a masonry bit to a diamond bit.

What is your goal?
a good substitute for this might be hypertufa fake boulders that are
plumbed as you like.

good luck.

My brother wanted a hole drilled through a large piece of slate. The best
place he found was the local stone masons, they had the right bits and water
cooled setup.
David