Many of the below, but not all of the listed forums would desire that you register with them....as certain images and data will not be available to the un-registered participant.
Before joining any of the forums listed, be sure to read their terms of service!
Major Forums....
WEBSITE
COMMENTS
U-Boat.net "General Discussions"
Net-Marine - www.netmarine.net Translated History Of The French Submarine Force
Foro U-historia Translated from Spanish
Foro Segunda Guerra Mundial Translated from Spanish
Deutsche U-Boote 1935 - 1945 Forum Translated from German
Axis History Forum "U-Boats" 
Feldgrau.net "Kriegsmarine"
Panzer Archiv "Marine WW II" - Translated from German
Deutsches Marine und U-Boot Forum Translated from German
Translated Archived Forum - Ended in Jan. 2009
Forum Marinearchiv "U-Boote" - Translated from German 
SUBSIM Radio Room Forums "News, Books, Films, and Models"
Sensuikan Forum IJN Submarine Forum
World War II Forums "Atlantic Naval Conflict"
SGM World Forum "War At Sea" - Translated from Spanish
Betasom - XI Gruppo Sommergibili Atlantici Forum "Betasom" - Italian Atlantic Submarines - Trans. from Italian
Tullys Port Forum IJN Submarine Forum
SubCommittee.com Forum Submarine Info Forum
Mille-Sabords Forum Naval Forum - Translated from French
Warsailors Forum The Merchant Navy Of Norway During WWII - Convoy Info
Norway During WW 2 Discussion About Norway During WW II
Atlantic Wall Super Forum Atlantic Wall In France - Translated from French
World Naval Ships Forums International Ship And Maritime Topics
Reibert Forum Military Forum - Translated from Russian
Tsushima Forum Russian Military Forum - Translated
Wermacht Awards.com Kiegsmarine Related Items
Blog Listings...
WEBSITE
COMMENTS
Wotan's Children
Book Review Blog
Photo-History Blog
