Do you remember that some fighter pilots could safely eject from underwater back in 1965? Could it be survived? One may wonder but a few ejections were reported. The transcript is below the video. Look at that canopy, it looks like it came from an F-8 Crusader:
If your aircraft has provision for underwater ejection, you have a ready-made, secondary escape route. Succesful underwater ejections can be made from any aircraft attitude – nose down, tail down, and inverted.
Escape by this method requires no preparation other than that recommended for normal seat ejection. There should be at least ten feet of water above you before you can safely eject. Never eject from the surface. With present systems, the chute cannot open with a zero-zero situation (which means at a height of 0 and at a speed of 0). The effect of free-falling 80 feet to water is little different than falling 80 feet to concrete. True, some lucky ones have lived to tell about it. But it is one hell of a gamble.
When you eject through the canopy underwater, the seat breaks through clearing the way for your body. Because water resistance imposes terrific forces on your head and neck, it is vital to hold the face curtain tight against your head for support. The forces of ejection might cause a momentary blackout. Immediately upon collecting your wits, disconnect yourself from the seat by pulling the emergency release handle breaking your restraints. Now, separate yourself from the seat. This is difficult. You will have to kick and swim violently even though you are disconnected.
If your chute gets hung up on the seat, do not waste time trying to clear it. Release your riser fittings and swim clear off the chute. Do not inflate flotation equipment until clear of the seat. Remember, surface slowly, exhaling as you go. Remove your oxygen mask.