Do you need to know how to swim on some of the water slides in order to get on them?

No you don't. Only the green one. I forgot the name. The one with the 10ft pool.

It is called shotgun falls

No, you can go on all the rides without knowing how to swim except for a green slide

No

There is only one slide that drops you in deep water.

You don't need to know how to swim except for the green slide that dumps you into a ten foot pool.