Do I have to know how to snorkel to take this tour?

It certainly helps to get the best view of the manatees but not necessary

They will help you learn. They helped my 8yr old and he got it down pretty good. Just be comfortable being in the water.

It always helps but it's really not hard to learn so I would say go and have some fun!

The tour guide will show you how to do it. It is easy to pick up and worth it!