What is the biggest documented ocean wave? How big was it? Where was
it? What caused it?

Hello Mickeyp

On 25 March 2004 it was reported that a wave measuring 170m (approx
550ft) was spotted off the tiny, low-lying Western Pacific nation of
Palau.

The news story can be read here:
http://www.abc.net.au/news/newsitems/s1073751.htm
http://cooltech.iafrica.com/science/311776.htm

If you are talking tsunami's then you have to look no further than the
mega-tsunamis.  A mega-tsunami is a wave large enough to cross oceans
and devastate land masses for miles inland.  It is estimated that 11
mega-tsunami's have taken place in the last 200,000 years so they are
rare!

In Lituya Bay, Canada, 1958 an earthquake triggered a mega-tsunami
that was estimated at being over 500m in height.

In 1737, a huge wave estimated to be 64m (210 feet) in height hit Cape
Lopatka, Kamchatka (NE Russia).

There is an excellent page on these devastating waves here:
http://armageddononline.tripod.com/tsunamis.htm

These pages are also worth a look:
http://www.csu.edu.au/faculty/health/aemf/HDS/chapter_9.htm
http://wcatwc.gov/physics.htm
http://www.ga.gov.au/urban/factsheets/20010821_7.jsp
http://www.frontiernet.net/~docbob/waves.htm

This is a fascinating subject, if you have any further questions
please ask for clarification and I will try to help you out as much as
I can.

Thank you!

I remember reading about conflicts between measurements of wave
heights by surfers in the US and the rest of the world. I think it was
the US who measured heights from the bottom of the trough in front of
the wave, while others were measuring down the back of the wave to the
ocean level behind. The former measurement is considerably greater, so
you might want to consider how the height is being measured in making
any comparisons.