I saw something in some science news on the net shortly before I started
getting interested in this subject, I'll have to find it again but the gist
from a quick skim was that some scientists now believe that ground strikes
are following an ionization channel opened up one of the high energy cosmic
rays that are constantly bombarding the earth. The strike may divert to a
high object near the ground but the ray path could also lead it to the water
or a lower object.

--
Roger Long