We didn't have a lot of time in Nassau so we didn't so much. We took at walk to Junkanoo Beach. Probably a 10 minute walk from end of pier (just turn right and start walking-there are signs). The beach was clean and not overcrowded.
This was fun. Don't expect a lot of sight seeing. You need to keep eyes on the road so you can't check out the land. We make one quick stop where the tour guide offered to take your picture for you. We stopped for about 1.5 hrs at Orient Beach (nude beach) to do what you want. Take a swimsuit and towel if you wish. No one on our tour brought swim gear. I would probably take the earlier tour (it's pretty early but more likely to run on time). When we returned, there were a lot of angry tourists waiting for their turn (about 1 hr late). It was starting to rain and they were concerned that they would run short of time (for returning to the ship). Since it was a RC excursion, the ship would certainly wait for them.
We decided to go to Honeymoon beach since we were going to be going on a somewhat expensive excursion in St. Martin. A 10 minute walk to a ferry boat which took us to Water Island and then another 10 minute walk to Honeymoon beach. The ferry was 10.00 round trip per person. No charge to get into the beach. The water was beautiful and was not a crowded beach (probably because you can't get there without crossing water). Once you are off the ferry boat, the 10 minute walk is up and down a big hill. Probably not that easy for someone that can't get around well. I did see some people being transported by golf carts (probably an option for someone that can't make the walk).