For the Japanese:
http://www.combinedfleet.com/atully08.htm
(combined fleet: Located and surveyed shipwrecks of the IJN).
Among those, there are some located and dived on by divers of USS Chanticleer only months after they had been sunk. Mostly for navigational markers, but also for Intel purposes as salvaging such items as documents and radar and coding equipment.
Diving on a recently sunk warship in tropical waters must have been one of the most nerve wracking experiences I can imagine.
The usual traps of wreckdiving plus unexploded ammo, oil, rotting corpses and sharks...
U boat wrecks can be found at uboat.net