found on : http://www.kwajaleinscubaclub.com/ very interresting site with wreck maps etc...
found on wiki :
http://en.wikipedia.org/wiki/IJN_6th_Fleet
Kwajalein in the Marshall Islands was the main base for Japanese submarine operations in the Pacific until it fell to the Americans in February 1944. IJN 6th fleet headquarters was relocated to Saipan in the Mariana Islands, which the fell to the Americans in July 1944 with the death of IJN 6th fleet commander in chief Admiral Takeo Takagi and most of his staff. The remnants of the IJN 6th fleet were based at Ulithi Atoll in the Caroline Islands until the end of the war.
It was used for submarines prior to the Pearl Harbor attack, I guess as a staging/refueling post. there was the Rio de Janeiro Maru (
submarine tender, flagship) at
Kwajalein.
11 November 1941:
The I-74 and the I-75 depart Saeki.
20 November 1941:
Arrives at Kwajalein.
23 November 1941:
Departs Kwajalein for the Hawaiian Islands.
there is more intel on :
http://www.combinedfleet.com/I-174.htm