Hi Melinda,
First of all, let me start by saying that my family absolutely LOVES
Disney's Typhoon Lagoon Water Park.
As far as I am aware, the only
Attraction at this particular Water Park which you will not be able to ride solo is
Gangplank Falls which is a raft ride in a giant inner tube which accommodates up to 4 people.
When my family were in line to ride this attraction whilst visiting the Walt Disney World Resort last year, we were asked if a single rider could join us in our raft as they were not permitted to have a raft to themselves due to health and safety reasons.
So rest assured that you will be able to enjoy all of the attractions as a single rider but you will be asked to ride Gangplank Falls with other Guests.
The snorkeling attraction which you refer to in your question, Shark Reef, actually closed in October 2016 to make way for a brand new attraction which is expected to open some time next year.
Wishing you a magical trip filled with memories which will last a lifetime!
Emma