Originally Posted by XL5
which insurance agency would underwrite the risk of an expensive aircraft, possibly x4, of becoming a submarine?
The same insurance agency that would underwrite a display aerobatic team flying 1940's vintage warbirds - none.
This is not more dangerous than all the other stunts display pilots do day after day, in fact it is a lot less dangerous than inverted ribbon cutting 20 feet above the runway, which you always see at airshows.
The dynamic pressure of water at 80 - 90 kts, which these guys seem to be doing, judging by the nose attitude, is immense. Any water skier would tell you that. You are in ground effect, which pushes you away from the water and these are guys who fly formation aeros in these aircraft. they know them very well.
If you are still wondering, look at picture of the singleton on page 1 of this thread. He is looking at the leader - flying formation in other words. He is obviously not worried about going in the drink.