The Walrus-class submarines are unusual in that instead of a cross-shaped assembly of stern diving planes and rudders, they mount four combined rudders and diving planes in an "X" configuration. This tail configuration was first tested in 1960 on the United States Navy's USS Albacore (AGSS-569), but has since been used only by the Walrus class, all Swedish Navy submarines since the Sjöormen class, the Royal Australian Navy's Collins class and the German Type 212A.
The submarines were in high demand by NATO during the Cold War since they combined a highly skilled crew with a very silent boat. At that time the majority of NATO submarines were either Nuclear or Brown water subs. After the cold war, the subs have been tasked for many intelligence gathering operations (still classified) in the Yugoslavian region, Iraq and Caribbean.
In 2007, the cabinet approved an upgrade of the four operational vessels and recruitment of additional crew to improve overall operational availability. The upgrades are focussed on near-shore operations and integration with new weapons. These include the US migration from the current MK 48 mod-4 torpedo to the mod-7 version.
In June 2010, Netherlands agreed to deploy one submarine to help combat piracy in the waters off Somalia. Possible missions could include, signals intelligence; going close to shore and intercepting pirates' radio signals, and the tracking of Pirate Vessels.