Make sure you go on a wale watching tour with a sizable boat.  We took
a small sail boat to Catalina Island from Marina Del Rey, the trip was
great, stayed the night at the Harbor in Catalina.  It was on the way
back that almost killed us.  High winds, Massive waves cresting over
the boat, sails flowdered and we almost lost stearing.  In fact we
almost colided with a big container ship.  Man those things are huge
close up.

Just make sure your on a big boat!

    That's why people get DSLRs.

    Again the reason for a DSLR: then you can add a decent telephoto
lens, and IS too for working from moving platforms, like boats.
Roger

If the whales are playing, they burst thru the surface and the window of
opportunity is small.  Anticipate - you'll miss the first one, but that
first one tells you where one is and it will probably jump nearby again.

If the whales are feeding, their forward movement is very small.  They
surface enough to breath thru the blow hole several times in a row in almost
exactly the same spot, then dive to feed.  That dive is when the tail
breaches and is usually the most interesting shot.  The whale will stay down
2-4 minutes (longer sometimes, but rarely) and will exhale strongly when
surfacing the first time - causing a burst of water into the air.  That's
what the boat crew will be watching for and steer toward.  They surface near
where they dive - they don't move forward much while feeding.

My personal preference is to meter and focus, and then switch to manual for
most shots - I don't care for the lag of the autoexposure and autofocus (I'm
an old manual kind of person).  Your autofocus MAY be fast enough, but
prefocusing ALWAYS works.  You know your camera best, but timing is
everything for these shots.

True, but this is a personal decision about what it does to shutter speeds,
ISO needed, etc.  Whales and boat crews don't concern themselves with your
angle with respect to the sun, so anytime the angle isn't right for the
polarizer effect, you're using a neutral density filter for no reason.
Again, a personal decision.

The whale watching tours that have been in the business for a while are
better at locating individual whales and getting close.  How close they can
get is limited by law and based on boat size - larger boats aren't allowed
as close as small ones (based on safety for the whales and the boat in case
of a collision).  My last effort was using a 200 mm on a 35 mm film camera
(about 4X normal), and the boat crew was very good at getting as close as
the law allowed, and stll the whales are small in the photos.  12X is a lot
better - be prepared to use it.

One more - a tripod probably won't have the intended effect.  The vibration
from the boat's engine(s) will transmit thru the tripod and cause unsharp
images (how would I know this?).  A monopod works better if you rest the
bottom of the monopod on your foot - this insolates the monopod from the
vibrations.  This might also work with a tripod if your have three or more
feet and unusually good balance.

Bob in Las Vegas