Tetanus vaccine can help prevent tetanus disease, commonly known as lockjaw.. Tetanus is a serious disease that causes painful tightening of the muscles, usually all over the body. It can lead to locking of the jaw so the person cannot open his mouth or swallow. Tetanus leads to death in about one in ten cases.
The most abundant dissolved salt in ocean water is sodium chloride. It is a colorless crystalline compound with the chemical formula of NaCl.
The ocean is about 3% salt. This varies a bit though, depending on where you measure it. Near where rivers reach the ocean, the salt content (salinity) will be lower. In fact, because salt water is more dense than fresh water, the river's water will actually float on top of the ocean water until it is mixed together.