Submarines have been using low and mid-frequency active sonar technology, a deafening soundwave that is dangerous even 300 miles from it's source. Some mid-frequency sonar systems can put out over 235 decibals, which is about as loud as a rocket launch.
Animals for hundreds of miles literally jump out of the ocean to try to avoid the sound. The damaging effects vary, bet are akin to decompression sickness causing internal bleeding and bursting organs including lungs and eardrums. When beached dolphins are reported this sonar technology is rarely mentioned in the news, although the link has been demonstrated.
The deepest area in the ocean is 35,800ft. or 6.78 miles deep. It is located at the Mariana Trench in the Pacific ocean. The average depth of the oceans is 12,500 feet.
An iceberg is a mass of ice that has detached from an ice sheet and is floating in the ocean. Icebergs pose an extremely dangerous situation for water vessels because only about 1/8 of the iceberg mass projects above the surface of the water.
The term "league" is used for measuring long distance over land and is equal to 3 miles. Just to make things confusing a nautical "league" is a different measurement & is equal to 3 nautical miles or 3.452 miles.
The Battle of Normandy was the decisive battle of World War II fought in the summer of 1944 between the Allied nations and German forces. The Normandy Invasion, or D-Day, is the largest ocean-based invasions in history with nearly three million troops participating. The battle stretched from the English Channel to Normandy, France in German-occupied Western Europe.
