Looking into this a bit more I came across ...
'h. Rogue waves are very rare large waves, probably due to unusual constructive wave interference. They are most frequent downwind from islands or shoals or where storm waves move against strong ocean currents, such as the Agulhas current off the southeastern coast of Africa. Rogue waves may sink or damage ships and often wash fishermen off rocks. Storm waves can often combine to produce waves as large as a 7-8 story building or 20-30 meters."
from: bss.sfsu.edu/ehines/geog646/646F02_class3.doc
By constructive interference I think they mean in phase amplification by wave strumming off of or refracted from an up current object, island in this case. An aerial photo of this appears below. Interesting stuff.
from:
http://www.math.uio.no/~karstent/waves/index_en.html
More about this at:
http://www.esa.int/esaCP/SEMOKQL26WD_index_0.html
http://news.bbc.co.uk/1/hi/sci/tech/3917539.stm
http://www.sciencenews.org/pages/sn_...23_96/fob2.htm