The damaged sub was escorted to Mumbai and made it back to the harbour only by Wednesday night. The Sindhughosh had recently undergone a massive two-year mid-life refit in Russia, costing over $ 80 million. It is equipped with Russian Klub anti-ship cruise missiles and is the only one in its class that is known to carry land attack cruise missiles. It is also fitted with an Indian sonar system.

In a similar case just over three years ago, another Indian Navy submarine suffered significant damage after colliding with an ‘unknown object’ while surfacing off the Goa coast. The subsequent court of inquiry could not establish the reason for the collision nor the object that had struck the submarine.

In the past few years, the navy has been hit by an increasing number of collisions and near misses involving its warships. Most of these events have occurred off the busy Western Coast that has a high density of shipping traffic.