Walrus class is one of the most advanced conventional submarines in the world in 1990s. The purpose of developing this class submarine in the Netherlands is not only to equip its navy, but also to push it to the international market. However, the latter goal has not been achieved, largely because the "walrus" class is designed for the use needs of the domestic navy and cannot flexibly adapt to the needs of the international market.

In view of this, the main Dutch submarine builder Rotterdam Dry Dock Company (RDM) adopted the modular design method when designing the new submarine "Eel", and introduced three models:1100t,1400t and1800t.

The design achievements and technical equipment of walrus class are widely used in "Sea Eel" class. Rotterdam Dry Dock Company believes that within 199, there will be a demand for 100~ 150 conventional submarines in the international submarine market, and it intends to capture 20% of them and sell different types of "sea eels" at a price of 225 million to 325 million dollars each. To this end, we have cooperated with Lockheed Martin Underwater Systems Company of the United States and Inges Shipbuilding Company of Litton Group, and conducted commercial and diplomatic mediation in response to the needs of Portugal, Malaysia, Indonesia and Egypt in the past year or two, and achieved initial results.

From June 5th to1October 5th, 2000, an industrial team led by Litton-ingels Company of the United States and participated by Rotterdam Dry Dock Company of the Netherlands signed a letter of intent with the Egyptian government to purchase two "sea eels" to be built at ingels Shipyard. If the contract can be finalized, the "sea eel" class will be the beginning of the resumption of the construction of conventional submarines by American shipyards. In addition, it is worth mentioning that although the Dutch government has banned the export of arms to the authorities of Taiwan Province Province, the authorities of Taiwan Province Province are still listed as one of the potential export areas of "Eel" class submarines.

In May of 20 13, the Dutch Ministry of Defence launched the "Walrus" class submarine upgrading and refitting project (LEP), aiming at extending the service life of the submarine to at least 2025 and enhancing its maneuverability in coastal waters. "Sea Lion" (S-803) will be the first modified and upgraded submarine of this class. The project will be carried out at the Naval Shipyard in Guerder, and Walrus (S-802) will be the last modified submarine of this class. "Sea Lion" is scheduled to resume sailing on 20 15 and "Walrus" is scheduled to resume sailing on 20 19.