This was hard because the last indigenous design was made sometime before the Second World War started and in the meanwhile there had been many developments, so there was a lot of catch up to do for the Dutch navy.

[5] A result of this was that during the designing phase for the new submarines the requirements constantly changed to fit in new research, developments and innovations.

The Politionele acties in Indonesia had cost the government a lot of money and at the same time the price of maintaining the old and outdated submarine fleet was high.

[11] The old submarines the Royal Netherlands Navy were operating were expected to be decommissioned in 1954 and their performance was already severely lacking at the end of the 1940s.

[12] The United States gave their consent and lent USS Icefish and Hawkbill of the Balao class, which were renamed and commissioned as HNLMS Walrus and Zeeleeuw during their stay with the Royal Netherlands Navy.

The name is based on their unusual design, instead of one or two pressure hulls the submarines of the Dolfijn class consists of three separate pressure hulls (cylinders) arranged in a triangle and enclosed in an external steel casing which separates the inside of the submarine into three parts.

[11] The designer was Max F. Gunning, who came upon this idea when he thought of a way to make sure Malta was properly provisioned during the Second World War.

[8] Zeehond was converted into a trials ship by Rotterdamsche Droogdok Maatschappij shipyard in Rotterdam in 1990 and used as a technology demonstrator for a closed cycle diesel air-independent propulsion system until 1994.