It is generally agreed that these submarines are outfitted with six 533-millimeter torpedo tubes suitable for the 21-inch torpedoes that are normally used on most submarines, including those of the United States. Some reports suggest that the submarines have a total of ten torpedo tubes -- six 533-millimeter and four 650-millimeter. Uniquely, the Soviet navy deployed the Type 65 heavy-weight torpedo using a 650-millimeter tube. The four larger 25.5 inch diameter torpedo tubes could be used to launch a long-range nuclear-capable submarine-launched cruise missile (SLCM). According to some reports the submarines may be capable of carrying nuclear-armed Popeye Turbo cruise missiles, with a goal of deterring an enemy from trying to take out its nuclear weapons with a surprise attack. Under a system of rotation, two of the vessels would remain at sea: one in the Red Sea and Persian Gulf, the other in the Mediterranean. A third would remain on standby. 

The project initially was structured to include an industrial team consisting of HDW and Thyssen Nordseewerke, lead by Ingalls Shipbuilding. The project, under which the boats would be built in the United States by Ingalls using US FMS funds, was cancelled in 1990. The crews of the submarines started training in 1994, and participated in the building process as well as in the acceptance procedures for weapon systems. Germany donated two of these submarines to Israel, which were delivered in 1997. Israel bought a third Dolphin submarine from Germany. The project to build the Israeli Navy's third submarine, named "Tekumah ," was launched in Germany on 09 July 1998 with the participation of Defense Ministry Director General Ilan Biran and other naval officers. Tekumah [T'kuma] is the Hebrew word for "revival." The third submarine arrived in Israel during mid-1999.

The first-of-class INS (Israeli Naval Ship) Dolphin was commissioned in 1999, INS Leviathan and INS Tekuma in 2000. The mission of the submarines is to carry out interdiction and surveillance operations and special missions. They replaced the Gal Class submarines, which entered service in 1977.

ISUS 90 integrated sensor submarine system
This system processes all of the information for the operator in many different variants, assists the commander with his decisions on the correct tactical behavior and assures the effective use of combat and defence weapons of the submarine. It is a flexible system allowing individual solutions to problems with different mission conditions and weapons.

The submarine has ten bow torpedo tubes. Four of the tubes have a 650mm diameter which could provide the capability of launching swimmer delivery vehicles (SDVs). With liners the tubes could be used for torpedoes. Six tubes are 533mm diameter for launching DM2A3 torpedoes supplied by STN Atlas Elektronik. The torpedoes use wire-guided active homing to deliver a 260kg warhead at a maximum speed of 35 knots to a target range of over 13km. Using passive homing and speed of 22 knots, the torpedo has a range up to 28km. 

The submarine can also be armed with mines. A wet and dry compartment is installed for deploying underwater swimmers.

The submarine has two periscopes supplied by Kollmorgen. 

The propulsion system provides a speed of 20 knots dived and a snorting speed of 11 knots. The range of the submarine is 8,000 miles at a surface speed of eight knots and over 400 miles at an economical speed of 8 knots dived. The hull is rated for a diving depth of 350m. The endurance of the submarine is 30 days.