We've been to N twice and walked the beach both times, once at night. I would not be at all concerned about it. It's not a populated area to start with. The beach you can walk is part of a peninsula with the Falmouth bay on the other side. The area is not populated. Unless a cruise ship was in, we only saw a guard at Red Stripe Beach and nobody else. When a cruise ship is in the area is much busier and security is about.
We were not really that concerned. It was more obvious than normal that we didn't have anything valuable on us, so I doubt anyone would bother us. We've also heard that the locals are pretty particular about not messing with the tourists in that area, since that's pretty much the main source of income, though that may just be rumor. Had someone been accosted, I'm sure it would have make Trip Advisor by now.
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