The news i heard from the locals is that they were diving at Mangrove, not blue corner, and mangrove is one of the safest sites in the area, because the point where you decent is usually max depth of 18m, and gently slope downward, unless you swim outward into the deep or oblivious to the current pushing you downward. Even when going into the deeper side, the last time i tried, i went into deco before i can reach 40m. This shows how far it is.
But from my understanding, the group were from Tulamben, which explained why they only got into the water at about 4pm, and they have to finish the dives so that they can go back to Tulamben in time.
That is why i always believe in diving with the dive centres at Nusa Lembongan instead of Bali itself, because the guys at Nusa Lembongan knows the sites and timing better.
Btw, i will be heading to Nusa Lembongan on the 12-14. Anyone will be there during that period?