Yes, Great Bay Beach is the one you can take the water taxi to. The taxi was $5.00 for DH and I and free for the kids (ages 3 and 4). It dropped you off right at the beach where we rented beach chairs for $10.00. We rented ones with the "Miller Lite" umbrellas and it included two free drinks and use of their restrooms.
I am not sure on the cost of the jet ski rentals. They did provide life jackets. It looked like they were run by locals so you may be able to bargain for the price.
The beach borders the town too, so maybe while DH jet skis, you can get some shopping in. My DH found beers for $1.00, I saw signs for 2 for $1.00.
I did not see any nudity on the beach.
Glad I could help!
Denae