In the 60's, Pakistan Navy ventured in the arena of asymmetric warfare, by ordering Midget submarines and swimmer delivery vehicles from Italy. These are generally known to be limited anti-shipping and mining platforms. Hence was the formation of Pakistan's frogmen branch, setup on the pattern of British SBS, but trained mostly by specialists trained by USN Seal Teams. The subject capability put IN on the defensive, as it's next to impossible to detect, and interdict. There were some successes and failures of the program but overall it served its purpose. IN even tried to acquire the same SDVs but could never operationally deploy them.
In the 90s, Pakistan upgraded the concept by acquiring larger midgets, with even more lethal capability. These "X-Craft" were mainly operated by the Frogmen, hence became the unique force in the world who were both crew and payload. Pakistani midgets or X-Craft gave India a tough time in many standoffs...After the decommissioning of Daphne Subs, the X-Craft were absorbed by the submarine force who operate them till today.
Now that these craft are up for replacement, while being fully operational but having completed their useful life, a great rethink of CONOPS and Doctrine is needed. Does Pakistan still need Midget submarines?
Meanwhile, great work is progressing in conventional submarines, where Pakistan is extending the life of existing platforms, and acquiring new ones. In a few years, Pakistan submarine force shall be 13 units, a formidable force to reckon with.
However, majority of our coast remains to be "Shallow Waters." That means, even conventional submarines cannot operate here, hence traditional submariners love to keep their keel clear of the bottom of all times.
So how do the midgets fit into the fray? The 100 ton craft have their pros and cons. Iran, out of desperation and compulsion, have undertaken both Midget and compact submarine programs. The midgets are derived from a Korean design, which in-turn is a copy of Italians. The compact submarine seems to be a purely indigenous design, and is progressing along. However after building the Ghadir class, Iran realized that they needed something bigger. The compact submarine, Fateh, is noteworthy, as it has almost the range of a conventional submarine, yet it can operate in shallow waters. This allows Iranian Navy to keep its Kilo class submarines in deeper water and on shore/fleet strike roles, and its compact submarine on defence / offense roles. This is a good lesson for all or any countries looking to narrow the shallow water gap.
As Pakistan Navy moves forward, they should think beyond the limited capability of 100-200 ton submarines, and think of a compact submarine platform, that is able to operate in shallow water, but has no limitation to operate in similar environment of a conventional submarine. This platform could be anywhere from 500 to 700 tons, and have suitable operational and technical capability for Spec Ops. If any such platform exists, it could be a superb force multiplier for PN, and fill the gap created by having only conventional platforms (if so in the future), that may be left by X-Craft when they are retired. I remain confident that Pakistan Navy and its leadership will make a wise and thought out decision as they move to narrow the shallow water gap in their underwater operations.