A few years back I flew Kahului-Kalaupapa (the accident airport) and Kalaupapa-Honolulu on a Cessna Caravan with another operator out there.
We were put in to a hold on the way in to Honolulu, and sat there circling several miles out to sea at around 2000ft VFR for 15 minutes or so. Whilst staring down at the sea it did cross my mind what would happen if the engine quit, because none of us were prepared with life vests or any instructions on what to do in the case of ditching.
After the flight I chatted to the pilot about commercial SE ops over water, his reaction was that it was so unlikely that it shouldn't even cross your mind.