You might be a mite cold in the 3mm at that time of year.  Even though
Hawaii is tropical, its waters can be chilly in the winter/spring months.
On the bright side, you have a good chance of encountering a humpback.

The good dive ops (which Alan already pointed out) leave from Kihei.  If
you're staying in the Lahaina area or further north, you have at least a 45
minute drive to the boat each way.  And since the boats require you to check
in at 6 a.m., that means you're getting up really, really early on your
vacation.  IMO, it's worth it.  But be warned.  You can shore dive at your
leisure if you want to sleep in and you'll also save big bucks since the
good dive ops (which Alan already pointed out) charge about $125 for a
2-tank dive.  IMO, it's worth it.  But be warned.

OK, here'e my 2 cents:

I just went to Maui with my family over Christmas. I normally dive Monterey
Bay,  in Northern California, and am hot-blooded anyway, and I saw guys
diving in Maui in shorts and a T-shirt over Christmans.  I could have,
easily.

For reference, I am a certified divemaster with over 100 dives.

We stayed in Kahana,  a few miles north of Lahaina, and my wife and eldest
daughter were diving and the youngest came along to snorkel, so I "settled"
on Lahaina Divers, Inc. , mostly to cut out the commute time to Kihei (hey -
I like boating better than driving).

I give them a C-. Their boats were newer (a plus, also a reason why I picked
them) - but one was SO new it didn't work right on it's day #3 (our  3rd
diving day ) - nothing serious, but indicative of this outfit. The boats
were packed solid, but most of the DM's were OK, so it all worked out to a
fair-to-middling 3 dive days. I mean, no injuries, no mishaps, nothing
serious. Just not the most enjoyable outfit I've ever dove with. They even
gave me a partial refund on my daughter's reservations when she had to
cancel due to illness.  So a C- is my decided opinion.

We dove the "must dive" trinity - A hot turtle spot (there are many, all
referred to as "Turtle Town" or "Turtle Reef" or something similar) ,
Molokini, and The Cathedrals at Lanai. The Lanai Cathedrals was blown out
(the boat  - the malfunctioning one- I swear to God - caught AIR on the way
back),  so we dove in a cove instead. Molokini was cool, very cool for my
kid who had a ray come up to her on the surface (!) , and "Turtle Reef" was
cool, but could easily be done as a shore dive (if you want to know where,
write me).

So what everyone told me was true:

- Maui is not a must-see dive destination, though cool in it's own right.
- Snorkeling is very cool there (I give snorkeling there an A! - if you want
recommendations, write me).
- Lahaina's limited selection of dive operators probably don't stack up well
(I have no direct knowledge) against those in Kihei.

I was very impressed, overall, with Maui. Nice people, nice balance of
development vs. preservation, etc. - I almost certainly will return.

Dennis

Thanks guys...
For the advice and the "entertainment" <GD&R>.
3 mils seemed thin from what I remembered when I was stationed at Pearl
Harbor in '65 (Navy).
Since I live in So. Fla. now, I doubt I'll go buy a heavier suit... might
rent one. Nowadays water's cold under 80 <BSEG>.
Tom