I was going to guess that or somewhere on the Cape Nat'l Seashore.
I drive out on Sandy Neck in Barnstable, and Crowes Pasture and Chapin Beach in Dennis, (though Chapin is rarely open to ORV anymore and only during low tides). I've never driven out on Chappy, nor Nauset. I did the outer beach in P-town years ago in my old '98 Blazer but I wasn't paying attention to the tides, which happened to be extremely high that day, and I almost lost my truck to the great Atlantic!
Question for you OP, when driving through loose sand in the 5th Gen, do you use 4H or 4L? I bought my '11 SR5 about 4 months ago but haven't taken it off-roading yet. I kept my '01 as a backup vehicle and use that for ORV'ing, kayak-carrying, fishing/ hunting and other dirty jobs. When driving out on the sand I would use the 4x4 system in center diff locked mode, but I know the newer TR4's are different. Eventually I'll have to get rid of the '01 and only then will I start taking the '11 offroad. Just wondering what mode is best for what situations. The owners manual isn't very clear about it.