Manta Ray is the shop I frequent in Monterey.  They are a good group.
Monterey Bay Dive Center is also a good shop.  (They are about 1 block
from each other and across the street from San Carlos Beach ("The
Breakwater").  Manta Ray is nice because they will do nitrox or trimix
fills while you wait.  At MBDC you will have to drop the tank and come
back later.

As for dive boats, I've been on three:  The Escapade, Cypress Sea, and
the Monterey Express.  The Monterey Express tends to be more geared
towards newer divers.  I used them once and was quite happy with them.
Last I checked they have steel tanks on board.  The Cypress Sea runs
the gamut from new divers to very advanced charters.  The Cypress Sea
also has a compressor and an enclosed cabin.  The Escapade is a very
nice boat and very fast.  They use Pressed Steel LP tanks.  Nitrox is
available.  They also run the gamut from beginner dives to tech
charters.  It would be hard to go wrong with any of them.

Escapade:  www.divecentral.com
Cypress Sea:  www.cypresscharters.com
Monterey Express:  www.montereyexpress.com

Oh yeah, the Cypress Sea has a swim step while the Escapade and
Monterey Express have ladders and are a little easier to get back on
the boat.  The crew on all three boats are top notch.

I'm not sure where you're coming from, but expect cool overcast weather
during the summer.  It may be 100 degrees, 25 miles inland, but it will
be 60-65 and overcast on the coast.

Have fun Diving in Monterey.

Kevin Metcalfe
nslckevin@yahoo.com
Pleasant Hill, CA

i worked in South san Francisco on a contract for a few months i hooked up
with California dive  great people

     Address: 715 El Camino Real
     San Bruno, CA 94066
     Phone Number: (650)588-4998
     (877)5-CALDIVE
     E-Mail Address: info@cadive.com

http://www.cadive.com/

http://www.cadive.com/monterey.htm