Two Indian Submarines Bump

Two Indian Kilo-class submarines collided last week when one that was trying to land hit the sub it was going to moor alongside. Excerpts:

Two Kilo-class 877EKM attack submarines collided with each other at the Naval Bay in Mumbai-half-a-km from the Gateway of India-last Monday.
Officials said the "minor accident'' took place when INS Sindhukesri was parked at the bay and INS Sindhuratna was returning from patrolling; the latter-being towed by a small tug boat -hit the parked Sindhukesri.
"The accident was not too serious as Sindhuratna's engine was switched off and it was being towed by a small tug. These are minor accidents,'' an official said, trying to downplay the incident.

This article has a "helpful" picture of what happened. I like to make fun of journalists who make basic mistakes in writing about submarines, but I can't help but think there was some translation error in this paragraph that appears in both linked articles:

Both 2,300-odd-tonne vessels have low noise levels. That could be one of the reasons why they got too close to each other without anybody noticing.

Yes, it's clear that two surfaced submarines, probably during daylight, couldn't notice each other -- when one was moored and the other was trying to park alongside -- because they were so quiet.