The San Fran is a pristine wreck, and pretty deep. I maxed out at 182 fsw in the forward hold. I did about 12 minutes in the hold and on deck at 165 fsw on 25% nitrox. Minor deco. Forward hold holds dozens of huge bombs, and there are small Japanese tanks on the deck at 165 fsw.
If you are comfortable with the amount of penetration it requires go into the machine shop of the Kensho Maru. I did it with a guide. Huge open machine shop with wrenches arranged on the wall, all the way form what was probably a 1/2 inch crescent to maybe a 3 inch crescent (which was a good 3 feet long), the bench grinders, pressure gauges, etc. are all still fully intact.
The Fujikawa Maru is also awesome. Huge open area above the engines, but a little tight to get in without touching anything. There's a compressor a little deeper in called R2D2 due to its resemblance to the Star Wars robot, great photo op. This is also a wreck that has incredible penetration possibilities. This one I also did with a guide, deeper in the engine room and the machine shop was incredible.
The Hoki Maru is also a dive you have to do. There are bulldozers laying on top of support beams, these I beams are the only things holding the bulldozers from falling to the bottom of the aft hold. They are corroded and bending under the weight.
The one combat ship we did was a destroyer that the dive op asked us not to penetrate due to the tight passageways and compartmentalization. That was fine, the bay is full of massive freighters full of military equipment with wide open holds and engine rooms/machine shops that require penetration but tend to be fairly open.
There's also one (forgot the name) where one of the hold is full of smashed Zeros. A dive within a dive.
