The mournful cry of a loon greeted my son Tom and me as we kayaked past the mouth of the Mystic River into sun-dappled Fishers Island Sound last Saturday.

A flock of hooded mergansers, passing through on a seasonal migration from the frozen north, skittered across the ripples, while the shiny head of a harbor seal, also in town for the winter, poked above the surface for a quick peek at the human intruders before ducking back under.

This serene setting seemed more reminiscent of Bar Harbor, Maine, than Mystic Harbor, Connecticut.

During summer, the harbor here is awash with power boats, sailboats, paddleboards, rowboats, occasional kite surfers and assorted other vessels, but on this mid-December morning, Tom and I were the only ones afloat.

“We have the water to ourselves. No motors, no boat wakes – not bad,” I remarked.

Tom nodded: Perfect.

Summer kayaking requires little more than shorts, T-shirt, sandals and lifejacket, but even on mild days this time of year, a prudent paddler outfits as if embarking on an Arctic expedition. The air temperature may have climbed into the 50s, but the water temperature dipped to 48 degrees. A kayaker who flipped over would lose dexterity in less than five minutes and become unconscious in under an hour.

Paddling in a drysuit works up a sweat, though, so Tom decided to cool off by intentionally flipping over, and then rolling back up.

“That’s much better!” he exclaimed, shaking salt water from his hair. I was content just to remove my hat.

We had launched from River Road on the Groton side, just north of the I-95 overpass. The parking lot fills up on summer weekends, but the only other car this day belonged to a woman walking her dog.

Propelled by an outgoing tide and brisk north wind, we rocketed downriver, with no particular destination in mind. Kayaking just about anywhere usually offers sufficient rewards, but the Mystic River is among several scenic, easily accessible waterways that make southeastern Connecticut such a paddling Mecca.

We first passed Mystic Seaport Museum to gaze at the whaleship Charles W. Morgan, and then continued south, beneath the downtown drawbridge. In warmer seasons, kayakers must steer away from the waterfront at Mystic River Park on the Stonington side to avoid a string of fishing lines, but Tom and I were able to paddle right next to the pier and exchange greetings with pedestrians.

After we passed the railroad bridge, near where the river forks, I asked, “Where to?”

“I'm thinking the east side of Masons Island,” Tom replied.

So we hooked left – or should I say, port – past Murphy Point and let the powerful tidal current pull us under the Masons Island Road bridge.

“Gonna be a lot harder on the way back,” I said, noting that we would then have to fight the ebb and wind.

“We’ll find some eddies if we stay close to shore,” Tom replied.

Soon, another decision: Continue due south, toward Enders Island, or bend east toward Latimer Point?

“Let’s head east,” Tom suggested.

It was a wonderful choice. After cutting through a narrow gap between Andrews Island and Latimer Point, the loon’s warbling call pierced the air. Then, when we rounded tiny Lyddy Island, the seal’s head popped up.

We stopped paddling and waited. Sure enough, one seal, and another, emerged only yards away. Though tempted to linger, we didn’t want to further disturb the protected marine mammals, so began paddling back north.

Then, a miracle: The wind shifted, and was now blowing from the south.

“This is one of 10,000 trips, when we have a tailwind in both directions!” I exclaimed.

An hour or so later, we were back on terra firma at the River Road parking lot, completing an eight-mile, more-or-less impromptu paddle.

Doesn’t get any better, on the last Saturday before winter.