Black(fish)net(stockings),
Ansel Adams? He did all his photography in black and white, used a tripod and did exposures that rarely used aperature openings larger than f/64! The latter two items are not ones that readily lend themselves to u/w photography. So, now, tell me how you use the "Zone System" (which Adams pioneered) and (previsualization of which he was the major proponent)? And, just out of curiousity, do you know who Minor White was?
Scubarat,
Sorry, for the diversion. People learn in different ways and, for some, a course is the best way to learn. If that is your mode, the class that I have heard the most good comments about is Cathy Church's on Grand Cayman. But, in all honesty, I have not taken her course or any others in u/w photography so I cannot tell you from a user's perspective. Never-the-less, I was in her shop/classroom when she was teaching and was impressed at her thoroughness. I saw the product of her students' efforts: very nice.
However, it was clear from the students' questions that they were all experienced photographers...
Now, where is all this leading? I guess it depends on your "land" experience. Have you done a lot of photograpy on land? What was its nature (snap shots, enlargements, darkroom experience, use of cropping etc.)? Do you want the same results from you u/w experience?
If you want snapshots to record your fun, probably a PADI course from a competent instructor will get you started. Here the best counsel would come from someone you know--did he or she take a course? How was it? Let's see some of your photos...
I am happy to discuss some more...if you like.
Joewr (not to be confused with Ansel Adams, Edward Weston, or Norbert Wu)