Our submarine force is not really the strength of our fleet just saying...
In comparison to our fleet - Yes
But In comparison to other navies - No
Look at this in perspective
Only 6 countries operate a SSN/SSBN, India being one.
Only 7 nations have more submarines than operated by IN (15):
Total Submarine Strength by Country
Of the above 7, 4 countries - Turkey, Iran, NK & even Japan cannot be said to be a MORE credible submarine power than IN. If we put UK & France above India (since they operate more SSN/SSBN), IN is still at Rank-6.
+ If things go well for IN, it will be getting 1 sub/year for few years & even 2-3 sometimes:
Currently Operated - 15
Kilo class - 10 (Upgraded, will be there atleast till 2020 & beyond).
Type 209 - 4 (talks of MLU, will be there atleast till 2020 & beyond).
Akula-II - 1 (leased for 10 years i.e. 2022, lease can be renewed).
Planned Inductions:
INS Arihant SSBN - 2013.
Maybe 1 more Akula-II by 2015 or so (speculating).
Scorpenes - 6, first one to be inducted in mid 2015 & than 1 every six months till 2018.
Follow-on scorpenes??? there were reports that IN will go for 3 more scorpenes but never confirmed officially, if true all 3 will be inducted by 2020.
INS Arindaman & INS ??? (of Arihant class) - well before 2020.
P-75I - 6, construction should start by 2015, with atleast 2 inducted by 2020.
So, if all goes well, IN will be operating around 30 subs (conventional & nuclear) by 2020, easily placing it in Top-3/4 Navies in the world.
P.S. But if our Naval & Political leadership had vision, IN's sub fleet would have been it's biggest strength rather than it's weakness.