Israel recently revealed that in 2013 its submarines spent 58 percent of their time at sea on combat missions while the rest of the time was spent for training. Israel currently has three Dolphin class subs in service and two more new ones (with more capabilities than the first three) entering service this year, followed by a third in 2017. The Israelis also admitted that their subs sometimes go far (to Iran and the Red Sea) from their bases on missions. Give that Israel is not at war with anyone with a navy, these missions are probably related to collecting information on the ships and ports of potential enemies. That would include Syria, Lebanon, Iran, Sudan and so on. The navy revealed that the subs undertook 54 “special operations” in 2013 and that was a big increase from previous years.
No details were given on what the special operations were but based on what kind of surveillance operations Israel has conducted in the past and what U.S. subs did in that area during the Cold War, the Israeli subs have probably been using their passive (listen only) sonar to collect information about ports and warships as well as deploying and retrieving larger electronic sensors placed underwater near where enemy ships operate. Israel may also be tapping underwater communications cables. For some of these operations the Israelis would use divers carried on the subs as passengers. Israel has a small force of naval special operations troops similar to the American SEALS and the British SBS.
All of the Israeli subs are built in Germany, where the local media periodically pretends to be appalled at what the Israelis actually do with these subs. Thus back in 2012 revelations in German media that the Dolphin class boats were equipped in Germany with a special hydraulic ejection (from torpedo tubes) systems for launching missiles with nuclear warheads caused a stir. This was actually misleading, as well as being old news. The Dolphin class subs have long had the ability to launch Harpoon anti-ship missiles and longer range cruise missiles from the torpedo tubes. It makes no difference if the warhead has high-explosives or a nuclear bomb in it. For over a decade Israel and Germany played down this capability. For example shortly after September 11, 2001 Israel denied that it had submarines capable of firing cruise missiles equipped with nuclear warheads. But the U.S. navy had reported spotting such missiles being tested by an Israeli sub in the Indian Ocean before 2001.
In 2000 it was widely reported that Dolphin class subs were being equipped with nuclear weapons. The 135 kilometer range Harpoon missiles were alleged to have been modified to carry a nuclear warhead and Israel. It was also asserted that Israel was developing a submarine launched 350 kilometer range cruise missile. Both of these weapons were launched from the subs torpedo tubes. Since then Israel has developed a new cruise missile, with a range of 1,500 kilometers and carrying a 200 kiloton nuclear warhead. These nuclear equipped subs were to provide an extra degree of security as all other Israeli nuclear weapons were in land bases and, in theory, could be wiped out by a surprise missile attack. A nuclear missile equipped submarine at sea would be much more difficult to find.
Germany continues to build Dolphin class boats for Israel. The first three arrived in 1998-2000. The second three Dolphins cost about $650 million each, with Germany picking up a third of the cost on two of them. The first two Dolphins were paid for by Germany, as was most of the cost of the third one. This is more of German reparations for World War II atrocities against Jews.
The three older boats have since been upgraded to include larger fuel capacity, converting more torpedo tubes to the larger 650mm size, and installing new electronics. The fuel and torpedo tube mods appear to have something to do with stationing the subs off the coast of Iran. Larger torpedo tubes allow the subs to carry longer range missiles. The larger fuel capacity makes it easier to move Dolphins from the Mediterranean to the Indian Ocean. Although Israel has a naval base on the Red Sea, Egypt, until 2012, did not allowed Israeli subs to use the Suez Canal. So the Dolphins were modified to go around Africa, if they had to.
As built the Dolphins could stay at sea for about 40 days (moving at about 14 kilometers an hour, on the surface, for up to 8,000 kilometers). Larger fuel capacity extended range to over 10,000 kilometers and endurance to about 50 days. The three new Dolphins have a fuel cell based (AIP or Air Independent Propulsion) system which enables them to stay under water for over a week at a time. The Dolphins are also very quiet and very difficult to hunt down and destroy. The first three Dolphins didn't have the AIP system.
The 1,625 ton Dolphins can carry 16 torpedoes or missiles and have ten forward torpedo tubes (four of them the larger 650mm/26 inch size). The Dolphins are considered the most modern non-nuclear subs in the world. The first three cost $320 million each. All have a crew of 35 and can dive to a depth of more than 200 meters (660 feet). The Dolphin design is based on the German 209 class subs but has been so heavily modified that it is considered a different class and only Israel has them.