We don't know why they're dead. Lack of information. Coulda, woulda, shoulda, speculation.

Did they lose consciousness prior to impact? Fuel leak in the cockpit? Fire? Stall it above the surface? We don't know. Impact a wave? We don't know.

The Twin Otter lands at roughly the same velocity as a sparrow, but it's got tall water-grabbing gear. For those who don't land on water or who haven't, there are a wild ideas about how to do it, and if the surface, or the angle to approach the surface, makes depth perception difficult (glassy water landing, or lighting that precludes depth perception), even birds sometimes can't find the surface and fly into it or stop flying above it. Just a fact of landing on water. Was it a factor? Unknown. I've run into a lot of pilots who suggest that they'd "stall it on" to minimize impact forces, completely oblivious to the fact that they'll nearly certainly make the landing worse.

Waves can be hard to gauge. Again, if someone hasn't landed on water, it's a moving runway, horizontally (often diagonally) and vertically.

The success of ditching also depends on whether either pilot was able (awake, conscious), and that information is also not in evidence. Radio calls were made while descending, but their condition at or just prior to impact is not given. Autopsy will provide that.

No doubt about it. That should have been a survivable event, something went wrong. Possibly flipped over on touch down and could get out of their harness or were disoriented hanging upside down in the water. That’s a terrifying thought.

Yes. Abrupt impact could have knocked them out. Military actually has practical training for egressing upside down aircraft in water (helos specifically), and it involves getting dropped into a pool, and then flipped over in a simulator... once the motion stops, you try to escape. Of course there are divers in the water for safety. It's a real thing. Also helo crew carry pony bottles, personally I would insist on that for an over-water ferry in anything not ETOPS certified. Even in an airliner, good chance that the O2 mask will work in that event.

Apparently, they’d been airborne for about 5 hours at impact. Turned around and reported fuel transfer problem.

Oh well. What a place to find yourself in.
Fair winds

There's a lot that can go wrong with fixed gear, ditching in the pacific, under duress. I don't know what the conditions were during this event, but a lot of time there's a marine layer just offshore from California. Pretty hard to estimate swells, sea-state, etc. when you can't see the surface. Lots of stuff in this scenario that could go really poorly.

How right that is. Landing a seaplane out in open water carries unknown hazards even when dead calm. Include evac after a gear down ditch, still alive to float/signal is the game. Not good. Knew someone survived a DC6 CFIT. Hit the surface in shallow water on 2nd approach to KIN. Subsequent nose gear collapse slammed the FE seat on top of the pedestal. 2 fatalities.

Yep. Dunker training.

Getting out seems so simple until you're upside down with water rushing in.

We did lots of different "dunks." Some of them with air, some with no air, some blindfolded, different seats, etc.

In all cases you wait for the motion to stop, put a hand on your egress point before you unbuckle, and never let go until you're free of the aircraft.

It got interesting when you or your buddy went the wrong way.