It was only after my son turned his back to the water and jumped off the 5-meter platform, his arms reaching into space, his legs flying up and over in an inversion that rang alarm bells deep in my Dad brain, that I realized he was attempting a backflip from high above the Müggelsee, Berlin’s largest lake.

This was a new trick — we’re not really a backflipping kind of family — and there was just enough time for me to think about travel insurance and why 13-year-old boys seem drawn to risk like moths to a blowtorch before he splashed into the lake, mostly upright.

Emergency averted, I took the long view: As long as no one ends up in a body cast, throwing ourselves into summer is why we’re here, right?

My wife and I took our two sons to Berlin in early August hoping to catch some of the city’s summertime vibe.

During the fall of 2016, we’d spent part of a sabbatical in the city. The beaches were closed for the season by the time we showed up, the paddleboards slid up into the rafters and pleasure boats marooned in winter storage. The feeling that we had missed something became more evident as weeks passed.

That autumn was blustery, and yet whenever we researched our Berlin neighborhood online, images popped up of sandy beaches, lakeside resorts and people lounging in swimsuits or skipping across the Müggelsee on a windsurfer. “Next time,” we began saying.

That turned out to be this August, and by then we had a shortlist of beaches, lakes and rivers to see.

Like Duluth, you can’t see the ocean from the German capital, but you can drive there in a boat. The city is landlocked, but coursing through its center and spiraling away from it are waterways that carry freight, passengers, tourists like us and all manner of watercraft. Berlin contains more bridges than Venice, about 120 miles of canals and rivers and a vibrant boating scene. The canals that crisscross the German capital eventually link up to the country’s major rivers: the Rhine, Elbe, Danube and Main. Thousands more miles of canals and rivers connect from neighboring countries, making it possible to spend weeks exploring Europe by water or venture to the North Sea.

We weren’t planning a voyage of that magnitude, not this time anyway. The city was our destination., and we started at a beach.

The Strandbad (literal translation: “beach bath”) Friedrichshagen sits on the north edge of the Müggelsee, not far from the apartment we rented while living here that gray autumn of 2016.

The beach couldn’t have been a more apt choice for our tale-of-two-seasons view of Berlin. The last time we had been there, it was winter. An ice rink covered the sand. Our hockey-loving sons skated quick laps before we retreated to a nearby cafe for hot drinks.

This time, temperatures soared past 90 degrees as we staked out a shady spot near the water. A few minutes later we had a happy surprise: A boy who recognized our sons from their time at the public school in Friedrichshagen two years ago introduced himself. They swam out to the high-dive platforms at the end of a dock extending from the beach. The backflipping soon got underway.

We watched from the shore mostly, lulled into complacency by our order of currywurst and radler beer (regular old beer, but with lemon) that we got from the Strandbad cafe. The cafe’s simple menu — you’d better be hungry for one of three types of sausage, French fries or a drink — belied how accommodating this simple beach was.

Everything needed for a day of swimming was here: an outdoor shower, bathrooms and changing rooms, picnic tables, some taller tables with umbrellas, a grass patch where families with babies stretched out on blankets, and more sand. A nice-looking bar next to the cafe wasn’t open yet. Tied up to the dock was a rentable houseboat. Every few minutes, another shaky customer of the paddleboard rental business voyaged out onto the lake.

The whole scene was so inviting that we weren’t too surprised when a wedding party set up on half of the beach, the bride and groom decked out in formalwear as their guests lingered under a party tent. In a city flush with historic churches, castles and parks, they chose this, I thought. Well played.

A river tour

Something clicked as we watched boats make their way across the water that day at the beach. The next day we headed to Berlin’s center, hoping to find a tour boat.

This is about the most touristy thing you can do in Berlin, other than wander under the Brandenburg Gate, but it’s a simple way to see some of the city’s iconic architecture.

The one-hour-or-so tour journeyed up and back on the Spree, the river that passes through Berlin’s heart. It has an industrial feel, but that’s changing. City residents have pushed the local government to clean up a portion of the river for swimming. The Flussbad (“river bath”) project would use natural filtration to clean the water and re-create the swimming areas that once existed there.

Swimming was on our minds the day of the boat tour, mostly because it was another scorcher of a day. We sat under umbrellas on the deck while our tour operator switched from German to English to talk about the buildings easing by, sometimes throwing in jokes that had a well-worn feel. (He explained that a church’s spire was topped by an antenna: “That’s because God has internet.”)

The boys liked the comfortable chairs, and a waiter swept past several times with cool drinks, but even the city’s magnificent architecture wasn’t enough to win me over. We needed a boat — without a tour guide, one that would stop long enough for a swim. We needed our own boat.

Boat for the day

We headed to the Wannsee, in the southwest corner of Berlin. The lake is home to sandy beaches, rowing clubs, marinas stocked with sailboats and lakeside homes for the wealthy, with boathouses the size of Minneapolis bungalows.

If the Wannsee sounds familiar, however, it’s likely for its dark past. It was in this privileged and beautiful environment that leaders of Nazi Germany met to lay their plans for genocide. The lakeside villa where they held their Wannsee Conference is a memorial and museum, one of the many ways that modern-day Germany ensures that people don’t forget the past.

We had come to enjoy ourselves on the lake, but we first spent a quiet hour sitting at a picnic table overlooking the water near the villa and its memorial.

Then we went to the rental boat office nearby, and after brief instructions, we hopped aboard our vessel. Anyone who’s spent time in a Lund fishing boat would have felt at home. Our “cruiser” came with a 9.8-horsepower outboard, a steering wheel, and a simple map showing us a route we could take around a large island.

It was early evening when we started out, a bit cooler than midday, and the light was just beginning to turn a golden hue as we approached the first real sight on our boat tour: Pfaueninsel, or Peacock Island. Today it’s a nature reserve and park accessible by ferry, but it was once a private playground for kings who built a castle and then stocked the island with a menagerie that included kangaroos, bears, alligators, chameleons and peacocks. Peacocks still wander the interior, hence the name, but the animals long ago became the first inhabitants of the Berlin Zoo.

It was while passing the island that we encountered a German tradition unlike any American custom. A sailboat, maybe 200 yards away, glided by with an elderly man at the helm. It wasn’t until he passed that we realized he was sailing buck naked, a fact that brought hoots of laughter from our sons. He wouldn’t be the last naked boat operator we saw that day; to the Germans this is a natural way to experience the outdoors.

We were halfway around the island when we passed under the Glienicke Bridge, connecting Potsdam and Berlin. During the Cold War, this bridge was a key link between East Germany and West Berlin and became a preferred spot for the exchange of captured spies. The “Bridge of Spies” was dramatized in the 2015 Steven Spielberg movie starring Tom Hanks and is perhaps best known as the spot where U2 pilot Francis Gary Powers was released by his Soviet captors in exchange for an East German spy.

This history was hard to reckon with the view we had of the bridge as we sat in the water, our motor idling. A gorgeous sailboat docked on the Potsdam side of the bridge captured our attention until a rustic-looking houseboat captained by a pair of young men floated past. Finally, the prow of a massive riverboat perhaps 300 feet long silently approached the bridge and then slipped underneath with just a few feet to spare. As it passed, we saw that its port of call was Basel, Switzerland. This “lake” we were on is part of the Havel River, and from here we could motor to ports of call near and far, if we had the time.

Instead we took a quiet channel around the backside of the island, slipping past lakeside châteaus with more boathouses, fantastic water views and resplendent landscaping attended to by robotic lawn mowers.

We had left most of the boat traffic behind in the Havel, so I relented as my sons begged to drive.

“It was really fun because you couldn’t really crash,” said the 13-year-old later.

“You could, but it was hard,” said the 11-year-old.

Fortunately, neither of them crashed as they expertly steered us through the rest of the canal. In this quiet stretch, a wooded forest lined both sides of the water, broken here and there by a simple house and, once, a canal-side restaurant that looked like a great place to kill a few hours. We emerged back on the Wannsee, almost done with our lap around the island.

Taking a cue from some of the other sailors, our sons stripped down and hopped into the lake for a swim on our final full day in Berlin.

The sun was now dropping. A sailboat slipped past us, its sail glowing orange with the last light of the day.

This summertime Berlin thing? We could get used to it.

@_mattmckinney