Sankalp Reddy’s movie is the first in Indian cinema to showcase underwater Indian Navy warfare in a war between India and Pakistan. The movie provides a unique glimpse of underwater war and delves into the historical background of individual submarines. Both the submarines, S-21 and PNS Ghazi, are remarkable in their design and structural systems. PNS Ghazi was renamed Ghazi after it was the US Navy Submarine USS Diablo (SS-479) from 1945 to 1963. As part of the Security Assistance Program (SAP), it was leased to Pakistan in 1964 for a period of four years. INS Karanj submarine was constructed by the Indian Navy and derived its name from its location at the time of construction in Maharashtra‘s Raigad district on the island of Karanja, also known as Uran Island. This is the origin of the ship’s name.

An architectural review of The Ghazi Attack-Sheet1
Submarine PNS Ghazi_©businessofcinema
An architectural review of The Ghazi Attack-Sheet2
Submarine PNS Ghazi_©wikipedia
An architectural review of The Ghazi Attack-Sheet3
Submarine INS Karanj (S21)_© wikipedia

Submarine design

The design of both the submarines S-21 and PNS Ghazi was exceptional. The design relies on various structural parts designed in a way that enables them to withstand both structural and water pressure loads in the ocean. This varies based on the shape of the hull design. The hull of both submarines is mostly cylindrical, consisting of a pressure hull with an outer hull and a floodable space. The space that stays submerged in seawater between the inner and outer hulls is known as the floodable space. This was depicted in the movie on two occasions: when a dead body was immersed in the sea and when a torpedo was manually launched. Additionally, the main stability of the submarine depends on the Main Ballast Tanks (MBTs). These MBTs, housed in enclosed cylindrical pressure hulls, run along the length of the submarine.

An architectural review of The Ghazi Attack-Sheet4
General arrangements of submarine_©marineinsight

The forward part of the hull is a good place for weapon storage and sensors. That helps in noise reduction from the forward alt. This area also includes torpedo tubes, torpedo launching systems, and operating tanks. The control room and communication room are near the accommodation and weapon area.

Stability of the Submarine

The process of surfacing and submerging a boat is crucial for its stability under water pressure. The ability to visualise underwater warfare plays a vital role in enabling the boat to avoid torpedo attacks, such as those from the PNS Ghazi. Submarines have two key conditions: being on the surface or submerged, which are determined by around 40% of the overall submarine structural design. The design is primarily based on the concepts of reserve buoyancy and weight distribution. The different depths underwater provided a significant opportunity for S-21 to evade PNS Ghazi. Once the submarine reached a depth of 300 feet, it became challenging to detect it using sonar. Evading torpedo attacks and being able to operate both submerged and surfaced were the only options available after losing the ability to use the submarine’s forward and backward sensors. Battery packs are essential for powering submarines and are typically made of hydrogen cells. The S-21 submarine required a higher amount of battery power due to damage from hitting mines. Each battery contains enough energy to support all submarine operations.

An architectural review of The Ghazi Attack-Sheet5
Submarine in Submerged and Surfaced Conditions_©marineinsight
An architectural review of The Ghazi Attack-Sheet6
Placement of torpedoes in flooded area_©marineinsight

Supply of Oxygen and Drinking water inside a Submarine 

Utilising distillation equipment, submarines warm salt water to produce water vapour, which eliminates salt and condenses into freshwater suitable for cooking, drinking, and personal hygiene. There are several ways to release oxygen on a submarine: compressed tanks, oxygen generators, and electrolysis-based oxygen canisters. Oxygen is released at specific intervals throughout the day or when the automated system detects a drop in oxygen levels.

Underwater acoustics 

As Leonardo da Vinci discovered over 500 years ago, the marine environment helps sound travel, sometimes over very vast distances. In the movie, another interesting aspect is locating the enemy submarine very precisely which helps them to control their actions and next move. This is only possible due to the sonar equation. Active sonar and passive sonar are the two categories. When an acoustic pulse (a “ping”) is reflected after coming into proximity to an object, active sonar records the echo. Similar to an ear, passive sonar records noises from its surroundings. These acoustic waves are detected by a receiver, known as a hydrophone. 

Factors affecting Submarine

The significance of submarines is important to understand, as they utilise the ocean’s transparency to play hide and seek. The ocean plays a crucial role for our military in locating enemies without being directly visible to them. Apart from military applications, there are many other factors to consider in underwater environments. While the ocean can provide a way to protect our land, it also raises questions about its impact on our ecosystem and climate. It’s crucial to consider these reasons not only for safety but also for understanding their potential future effects. One of the major issues of climate change is difficulties in different military operations. Like the capability to detect, identify, and geolocation enemy platforms due to the effect of sensors such as laser, solar, and radar. The question is whether it will continue to increase and by how much. This poses a serious threat to global security. Ocean life plays a significant role in this. Even a minor factor affecting climate issues can lead to numerous problems for us in the future, including in our military submarines.

Reference list:

Gilli, A., Gilli, M., Ricchi, A., Russo, A., Carniel, S. (2024). Climate Change and Military Power: Hunting for Submarines in the Warming Ocean, Texas National Security Review

Available at: [Accessed: 07 June 2024]

Chakraborty, S. (2019). Introduction to Submarine Design, Marine Insight

Available at: [Accessed: 07 June 2024]

Chakraborty, S. (2021). Understanding Stability of Submarine, Marine Insight

Available at: [Accessed: 07 June 2024]


She is an architect from Mathura with a strong interest in heritage conservation, adaptive reuse, urban regeneration, and research. She graduated from Dayalbagh Educational Institute, Agra. She has previously worked as a volunteer in different regions of India. She has a keen interest in social engagement activities, as well as research and writing skills. As an architect, she has realized that her objective extends beyond creating new designs to include conserving heritage and contributing to the well-being of future generations.