Hi sssilverdollar,
I dove out of Alpena for over twenty years from the early 70s through the early 90s. There is great wreck diving there for all levels from newbies to highly experienced teckies. There is a thread, Thunder Bay Alpena, Michigan Wrecks, under Wreck Diving in the Technical Diving Specialties section with information on a number of the most popular wrecks. Take a look and we can discuss there, or here if you have more questions. As for diving conditions; There is rarely a current on any of the wrecks. However there can be surface current affecting safety/deco stops depending on wave & wind action. Water temp by late summer will be in the 60s to maybe low 70s in the first twenty feet or so, 40s to 50s down to 80 feet or so and low 40s year around much below that. Drysuits are definately a big plus,some would say a necessity! I had quit diving up ther before the zebra mussels had taken over the Great Lakes and I am told diving up there now is a whole new experience because of how much they have cleaned up the visibility.I have heard visibility up to fifty feet is common now but was practically unheard of back when I was diving up there. They have been keeping bouys on the wrecks in the preserve for years but with budget cutbacks they may not be marked now unless the local are keeping them up.
Have fun!
jimthediver