There is 96 steps and no elevator is available.
The tower was constructed in 1980. It is the biggest underwater town in eastern Asia. The observatory is located 8m under the sea level. There are 24 windows that offers you the 360 panorama view of pacific ocean.
Because this is located where hot and cold water meet, there are various kinds of fish live around the tower. Over 20 kinds of fishes you can enjoy, and sometimes, you can see sharks.
There are ocean museum, restaurants and gift shops around the tower.
Official Web site: http://www.bay-web.com/leisure/katsuura/