October 6,2008:  The U.S. has retired the Mystic, the  second of its two 49 foot long rescue subs. The other one, the Avalon, was retired in 2000. These were built in the late 1960s, in response to the 1963 loss of the American SSN USS Thresher. Neither ever had to be used, and rescue has now been taken over by the SRDRS (Submarine Rescue Diving and Recompression System). While the minisubs had to be transported by another SSN, the SRDRS is a modular system that weighs under 200 tons and can be flown anywhere on the planet within 72 hours (faster depending on the distance and availability of heavy transport aircraft.)

The SRDRS was designed to be operated from most merchant ships. SRDRS consists of two main components. There is the rescue module, which is a remotely controlled submersible that descends to the stricken sub, attaches itself to the rescue hatch, and has room for 16 sailors. Once on the surface, the sub links to a decompression chamber, where the sailors have to stay for a while to acclimate them to surface pressures (and prevent the bends). In addition to the rescue vehicle and decompression module, there is support equipment. There are also smaller underwater vehicles and pressure suits for divers. These are flown in first, to explore the stricken sub in detail, clear any debris from the subs rescue hatch, and basically gather information to the actual rescue can be carefully planned.

Last year, Britain, Norway and France have completed the construction of the NATO Submarine Rescue Vehicle (SRV). This is very similar to the SRDRS. NATO SRV was a $95 million project that resulted in a deep water rescue device that can be airlifted to anywhere in the world on short notice, fit on the deck of at least 140 identified ships, and mate with the escape hatches on most of the worlds submarines, and carry up to 15 men at a time to the surface.  This system is shipped in eleven waterproof cargo containers, that can be flown by military or civilian cargo aircraft. Including flight time, set up time on the ship, and movement time to the site of the distressed submarine, the NATO SRV should be able to get there and have the SRV in the water within 72 hours. The SRV itself is 31 feet long and weighs 27 tons, has a crew of three and can go as deep as 3,000 feet (which is the maximum depth for most submarines.)

The U.S. and NATO systems are very similar, but not identical. The basic idea behind this modular design is to enable the rescue system to reach the stricken sub as soon as possible. Once the air runs out down there, rescue is no longer possible. All the navies of the world are invited to modify, if necessary, their rescue hatches (usually just the main hatch on the top of the sub) to accept the U.S. or NATO rescue vehicles. If they do that, the NATO or U.S. rescue systems (depending on whose is closest) will be sent to attempt a rescue. The U.S. systems is based in California, the NATO one in northern Europe.