The Saurichthys class originally had 4 ships but two had been scrapped in the early 30's and the other two reduced to training boats only. The Grey Havens Fjord was their training area.
The Otodus class were the first full fleet sized submarines built by the Zealandian Navy. By the outbreak of WW2 the boats were pretty much obsolete and were kept to patrol the close areas around Zealandia and were also used as part of the training fleet.
The Gogonasus class were a mixed submarine minelayer. The rear of the sub was fitted with a conveyor belt that delivered the loaded mines to the rear of the ship where they were launched from. The boats were built for offensive minelaying in enemy waters. Originally a class of three, only two made it to WW2, one disappeared on a training patrol. Fisherman reported hearing an explosion in the area the boat was reported to be but never saw anything. It was decided a mine had a problem within the ship while going through training evolutions and caused an explosion which sunk the boat. They were found to be useful boats. One of their main area of operations was around Singapore and the entrances between the East Indies Islands and the Solomon Islands area where they laid many small fields that caused many problems and some successes in sinking and damaging Japanese merchant and warships.
The Ischyodus Class were an experimental type of boat in the submarine cruiser genre of which many navies were trialing boats to augment their offensive capabilities. Armed with two twin 6" turrets, it was felt these guns would be big enough to sink smaller enemy merchantmen with only a few hits and save the much more expensive torpedoes for the biggest targets.
The Tristychius class was under construction when war broke out and a further four units were ordered then these were replaced in production by the Arandaspis class.
The Squalicorax was to be a medium sized boat that could be used in confined waters or in the open oceans. Higher priorities than submarines meant that production of the class finished in 1943.
The Arandaspis class were the biggest of the normal fleet submarines to be deployed into the Pacific. Two squadrons of eight boats each were ordered in January of 1940 (8) and January 1941 (8) under the Emergency War production estimates. All 16 boats were completed but the boats still under construction in 1944 had their construction slowed considerably, the last being completed in February 1946. Rebuilt during the late 40's to early 50's the class served through to the 1970's
