PADI offers nitrox certification without a formal open water dive. In fact, I recall my class really only met once to go over the material and take the test. This can definitely be done in an afternoon (with a small class, of course). Your experience will vary based on agency, instructor, and class size. Please be sure to ask how long the class will take _before_ registering for it. I had a friend who said that his nitrox class took 6 class hours over 2 different nights.
I would recommend getting nitrox certified by an instructor you know and like. As with all classes, you'll get out of it what you put into it. During the course, ask your instructor any questions you have about operating your own computer. He/she should have the patience to sit down with you, your computer, and the instruction manual...so that you eventually understand the idiosyncrasies of your computer. Also, the instructor should have at least one functional oxygen analyzer so that you can do a hands-on demo.
That being said, the largest dive shop that does instruction in the San Diego area is Ocean Enterprises (
San Diego Scuba Diving Store and Training: Ocean Enterprises - Ocean Enterprises). There are several good dive instructors there. That's where I got my nitrox certification.
Important: As much as I hate hurling negative comments about a local dive op, I want you to have a good experience. Don't let Ocean Enterprises talk you into doing your Yukon dive on their affiliated charter operation called Dive Connections. I would look elsewhere -- even if it costs a little more. My dive buddies and I have had a few bad experiences with Dive Connections.
The Yukon is an ideal dive for 32% nitrox. You would be hard-pressed to exceed the maximum operating depth of that mix on the dive (unless you take a shovel) -- the ocean floor at a depth of 105 fsw with the ship sitting on its port side.
In case you intend to bring your own nitrox tank onboard a dive boat...you can get nitrox fills from San Diego Underwater Adventures (
SDUA Home Page). They are a very trustworthy operation.
I can recommend the following dive boats:
1.
The Lois Ann. Solid, experienced dive op. Nitrox available - $8 80 cuft, $12 100 cuft.
2.
The Marissa. Nice boat. Not crowded. Friendly staff. Good food. Don't know about nitrox availability.
3.
Waterhorse Charters. New kid on the block. Nice, new boat. Soft weights. Friendly staff. Pricey. Nitrox avail - $12/tank.
Have fun and dive safe.