He did not know much about the effects of underwater explosions.

Until now, he had no way of knowing the effects that an underwater explosion might have on a submarine from a short distance.

Two heavy underwater explosions were heard as the submarine submerged.

A trail of large air bubbles was followed by a massive underwater explosion as U-754 went to the bottom with all 43 hands.

"An underwater explosion from a mine wouldn't damage the legs?"

Forty-five minutes and 18 depth charges later, two underwater explosions were heard.

One of our ships noted an underwater explosion in the area - no, that's not right.

Sorry about the delay, but Pigeon had trouble with the radio, as a result of the underwater explosion, they say.

The second attack was followed by underwater explosions, and debris rose to the surface.

A bubble jet is caused by an underwater explosion which changes the pressure of water, and whose force can cause a ship to break apart.