In the open ocean tsunamis can apperar very ery small with a height of less than 3 feet. tsunamis will somtimes go undetected until they approach shallow waters along the coast. These waves have a very large wave lenght up to several hundred miles that is a funtion of the depth of the water where they were formed. Although these waves have a small height, there is a tremendous amount of energy associated with them.As a result of this huge amount of energy these wavescan become gigantic as they approach shallow water.As they crash upon the shore there height depends on the underwater surface features. They can be as heigh as 100 feet or more. In 1737, a huge xave estemated to be 210 feet in height hit Cape Lopatka, Kamchatka Russia.The largest Tsunami ever recorded accored in July of 1958 in Lituya bay, Alaska. A huge rock and icefall sent water surging up to a high water mark of 1640 feet.It's no wounder that these waves can cause such massive destruction and loss of life.