I can see lots of areas that are in the water. Some caves and stuff look like they will need a boat or need link to swim or something. When i jump into the water he drowns. There must be something that allows link to jump into the water and swim though. How do i do it?
You will find the item that lets you move through the water in one of the temples. Zelda games are great for giving you the items you need when you need them. IF you think the way forward is through the water than you are not going the right way. Wait until you get to the water temple before you start to worry about finding this item.