Do the dock ladders need to touch the bottom ? If not what keeps them from bending ? Its 10 feet deep at our dock with no support under the dock

Correct! We use them on swim rafts too and they don’t touch bottom. They are very strong.

There must be something under the end of the dock or at least close to it. Most of the ladders are four or five step and they don't have to touch the bottom because of the way they are constructed