My stomach dropped the moment I saw the sign on the lockbox: “Stash your phone for a true escape into nature. We dare you!”

It was bad enough that there was no Wi-Fi. But I knew I wouldn’t be able to resist taking a million photos so I could later Instagram everything about my night in a tiny house on the beach . . . right in the shadow of the Verrazano-Narrows Bridge.

For $150, you (and a guest, if you wish) can “rough it” in a 200-square-foot cabin just off Fort Wadsworth beach in the Gateway National Recreation Area on Staten Island’s south shore.

Thankfully, you don’t have to fear midnight bathroom breaks among squirrels. The three tiny houses each have their own bathroom, complete with shower, as well as a bed and a kitchenette equipped with a two-burner stove and a handful of cooking utensils. (There’s no fridge, although there is a cooler. BYO ice.)

From now through Labor Day, vacation-rental company Getaway — whose sole specialty is pint-size properties — is running the pop-up. The program’s already hugely popular, with slots snatched up as soon as bookings opened last month. Luckily, Getaway held back half of the reservations and releases a few every morning at 10 a.m. at www.Getaway.house.

“The star of the show is nature,” said Getaway co-founder and CEO Jon Staff. “I go to a bar in Brooklyn, and everyone’s looking at their phones. Here, no one has their phone out.”

Instead, on Fort Wadsworth beach, fishermen and joggers take to the sand as ships of all stripes enter New York Harbor. The beach isn’t debris-free, but then again, this ain’t Bali. Each home does offer a great view, as a window above the queen bed looks out on trees, the beach and Lower New York Bay. Should you still need a way to occupy yourself, there’s a small book collection — including Robert M. Pirsig’s “Zen and the Art of Motorcycle Maintenance” — and a deck of cards. A vintage-looking radio can amplify music played from your phone (another reason not to lock it up).

Warning: There’s no air conditioning. Screened windows help, and Getaway says fans are coming.

Additional warning: There’s no hot water, so shower at your own risk — although the swanky Malin + Goetz products ease the pain.

Don’t get freaked out by the waterless toilet. At the touch of a button, waste gets shrink-wrapped and disappears beneath the seat for removal by Getaway staff. Also amazingly space-age is a powdery substance called InstaFire, complimentary with each cabin, which ignites like magic in the on-site fire pit. I couldn’t get the provided logs to catch flame, however, so it was marshmallows roasted over the butane-powered stove top for me.

It was a pretty novel staycation — and only an hourlong bus ride from Manhattan — for this girl accustomed to a bodega on every corner. Plus, I only had to kill two bugs.