Jetties is conveniently located, has the best amenities of any Nantucket beach, and has a nice playground area and fun tide pooling opportunities to keep the kids busy.
When I look for a beach, though, I look for sand, surf, and sights.
Jetties' medium-to-coarse sand is nothing to write home about, there is no surf (being a bay-side beach), and it isn't particularly beautiful to me. While you may get good glimpses of sailors and kite surfers doing their thing, enjoy the convenience of the OK restaurant, or have fun playing ball on the wide expanse of sand, I would trade Jetties for any of the south-facing beaches any day of the week.
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