The conning tower is the highest point of a submarine. The hatches through the tower(there are more than one) were left open, this allows fresh air to circulate below which is refreshing for the crew. A rogue wave is a wave higher than the average waves experienced during any given sea condition; water ingress down the tower inside the submarine caused an intense electrical fire in an exposed electrical panel.

The open hatches at sea are not unusual on a diesel submarine, but in rough weather it is policy to have one watertight tower hatch closed. Since these investigations are highly self critical, and very detailed, you can be assured that the sub was not expecting abnormal sea conditions. The root cause of the fire leaves us guessing at the possibility of a design error, some water will always find its way through the tower. Perhaps inexperience was a factor, because they had no time for extensive sea trials before bringing the sub home.

Design is an issue because one should always expect some water to ingress through the tower. An exposed electrical panel should not be so placed, and definately should be protected. Inexperience may also be a factor due to limited sea trials prior to the voyage. Perhaps it is another example of how we progress in time and technology, but with little wisdom. Any way you view this, the officers and crew are not to blame for the wave. Having been identified as a problem, It is unlikely this will happen again.

Yours, Aye. Dave