National Interest https://nationalinterest.org/blog/buzz/how-sink-3-billion-dollar-nuclear-submarine-leave-hatch-open-208170
Wiki: https://en.wikipedia.org/wiki/INS_Arihant
Popular Mechanic: https://www.popularmechanics.com/military/navy-ships/a14783891/someone-left-a-hatch-open-and-crippled-indias-dollar29-billion-submarine/