While kayaking last week through a churning, tidal rip just off New York’s Plum Island, site of a top-secret, animal disease laboratory, I jokingly suggested that we seek refuge ashore.

“Except,” I added, “we’re probably already in someone’s crosshairs.”

No kidding. Only about 15 minutes later, after Dan Bendor, my son Tom and I punched through the chop and edged to within 100 yards of land, a white pickup truck materialized from behind a hill and rolled to a stop facing us.

The driver never got out, but the message was clear: Don’t even think about landing.

Not that we seriously considered trespassing — the U.S. Department of Homeland Security tightly controls access to Plum Island, where scientists have been studying various pathogens since 1954.

Longstanding rumors of anthrax research, always denied by government officials but a recurring theme in books and movies, have contributed to Plum Island’s mysterious, forbidding vibe.

The island’s reputation, though, could be rehabilitated when the research lab moves to Kansas in 2023.

The government initially proposed selling Plum Island to developers when lab relocation plans were announced more than a decade ago; among those interested was Donald Trump, who hoped to build a golf resort.

But last year, Congress passed legislation that environmental advocates expect will lead to Plum’s designation as a wildlife refuge. Scientists have recorded 227 bird and 280 plant species there.

Along with its starkly institutional government buildings, the island houses the remnants of a Coast Artillery post, later known as Fort Terry, that was built in 1897. After World War II, it the fort was assigned for a time to the Army Chemical Corps.

“The part that doesn’t looks like a horror movie set is beautiful,” Tom said.

He, Dan and I had another reason to avoid taking a break on Plum: We needed to keep going quickly to cross treacherous Plum Gut, looming just ahead, before an ebb tide turned this mile-wide passage into a tumultuous cauldron. The website coastalboating.net rates Plum Gut the fifth most-challenging cruising waterway in the Northeast.

By avoiding delay, we made it through unscathed, and remained focused on dodging ferries that plied between New London and Long Island’s Orient Point.

The three of us — Tom aboard a single kayak, Dan and I paddling a tandem — then landed on a beach at the northern tip of Orient, well distant from the ferry terminal. If we weren’t so wasted by the heat, we might have rejoiced reaching the halfway point on what turned out to be a nearly 30-mile excursion.

Dan and I have paddled this route several times over the years; it was Tom’s maiden Long Island voyage.

Gulls cried; cormorants perched on rocks; schools of bunker, pursued by stripers and bluefish, roiled the surface; a lone seal popped its head up for an instant and dived back down.

We had launched that morning from a beach off New London’s Pequot Avenue amid light winds and flat seas — ideal conditions if it weren’t for temperatures and humidity in the high 80s. Tom cooled off by rolling his kayak upside down and flipping back up; I found it easier to squeeze a wet sponge over my head. Tom and I also drank gallons of water, while Dan guzzled bottles of his homemade “bug juice” concoction.

With a flooding tide, we set a south/southeast course with the expectation that the current would pull us close to Plum Island. That worked well until we approached a stretch northeast of Plum called The Sluiceway, where tide rushing into Long Island Sound swept us into gnarly turbulence.

“This isn’t fair!” I grumbled.

Eventually, though, we skirted confused seas, found an eddy and rode the tail end of the flood past Plum, through the Gut and onto Orient.

I glanced at my watch — 1 p.m. We had only 10 minutes before the start of the ebb — hardly enough time to gobble sandwiches, gulp water and climb back aboard for the 14-plus-mile paddle back to Connecticut. Had we lingered, the current would have dragged us back into the Gut.

Waterford’s Millstone Power Station, faintly visible in haze, served as a navigational aid, keeping us west of the busy ferry lane. We still had to watch out for fishing boats, sailboats and other vessels, including an enormous tanker that rumbled by about a mile north of us.

As we proceeded toward the Connecticut shore, familiar landmarks slowly came into focus: Rocky Neck State Park in East Lyme, Black Point in Niantic, Seaside and Harkness Memorial State Park in Waterford. At last, the home stretch!

But wait, Long Island Sound had more surprises: a nasty tidal rip at Bartlett Reef, followed by sloppy chop at Little Goshen Reef and Goshen Ledge off Waterford.

Finally, we passed Waterford Beach and Ocean Beach Park, both packed with swimmers.

It was tempting to paddle ashore and jump in, but our determination to finish the trip prevailed. Also, the water was filled with lion’s mane jellyfish, whose tentacles can deliver a painful sting. Cooling off could wait.

Finally, after paddling a total of more than six and a half hours, we weaved past Shore, Middle and Cormorant Rocks at the mouth of the Thames River.

Just as I unsnapped my spray skirt while preparing to land, the wake from a passing ferry washed into my cockpit.

In chilly weather, this would have provoked a salty outburst, but on a sweltering day, the cool splash felt absolutely delightful — the perfect finale to a long but rewarding day on the water.