My kayak then was a simple ash-wood and brass frame that slipped into a polyethylene hull, much like a tent. On the dock of a sailing school in front of our building, I’d assemble it in about 20 minutes and launch it, sometimes directly to my home in Queens, rounding Manhattan’s Battery to the East River. More often my course was set by a whim. Wherever I landed, mass transit was there to carry me to my door. Today, as then, a paddler needs permission to launch or land on a waterfront, whether by handshake from a private dock owner or a seasonal park permit.

Once you’re afloat in a seaworthy vessel that’s equipped with required safety gear, however, you’re as legit as a cruise ship.

Urban island hopping by paddle is easier today, thanks to two factors. First, nonprofit community boathouses with kayak and canoe fleets for public use are flourishing. Second, computer-aided design, laser-cut modeling and 3-D printing have ushered in a golden age of innovative portable designs that collapse into a backpack or suitcase. Kayaks, rafts and stand up paddleboards fold like origami or inflate to a rigid and streamlined shape. Some, like the Pakayak Bluefin 14 ($1,795, pakayak.com), are composed of modules that pack inside each other like Matryoshka dolls or even stuff into a bag along with other gear. These craft can weigh between 7.9 lbs. and 59 lbs.

“Manufacturers are targeting people who don’t have a lot of space to store things, like a cramped-studio-apartment dweller,” said Matt Powell, vice president for Sports at NPD Group, a market research firm based in Port Washington, N.Y.

The advantages of owning backpack boats go beyond their ability to shrink. There’s the independence and enjoyment of paddling one way all day, without having to double back and return to base. I recently paddled my Sea Eagle 385ft Fast Track inflatable (from $1,334,seaeagle.com) 115 miles from New York’s Raquette River to the heart of Montreal, through Akwesasne territory (with tribal permission) and down the Saint Lawrence Seaway, only to bus back to Grand Isle with the boat.

Such boats also encourage spontaneity; you can haul out to enjoy waterfront festivals, dock-and-dine, or linger to get that nature photo. One night, a buddy and I, full of mochi ice cream from the waterfront Mitsuwa market in Edgewater, N.J., paddled the Hudson through the darkness toward the steady whump-whump throb of a bassline to discover Wigstock unfolding on a Chelsea pier. Our unique perspective from the water offered us a split-screen view of the drag performers’ polished stage reviews and simultaneous frenzy of preparation backstage. We weren’t concerned that our lollygagging would cause us to lose our tidal current since we could pack away and catch the subway.

Another plus: When you’ve reached your limits or weather looks daunting, you can head to shore with no shame, no hassle.

The best urban paddling safety maxim comes from Ralph Diaz, author of “The Complete Folding Kayaker”: “Be seen. Be heard. Assume you’re not seen and not heard.” To be seen, choose boats and gear in bright neons and attach white, red, and green navigation lights to your kayak at night. A GPS Personal Locator Beacon attached to an always mandatory life vest could also rally help to you if all else fails.

To be heard, bring a smartphone along in a waterproof case, and secure a marine whistle and a waterproof floating marine radio to your life vest. A good, basic example of these specialty walkie-talkies is the Standard Horizon HX300 ($129.99, standardhorizon.com). Before you embark, check in with your local Coast Guard Auxiliary to stay informed about other vessels and keep up with the nautical “rules of the road.” The New York City Water Trail Association (nycwatertrail.org) has a great tipsheet for responsible urban paddling.

Paddle smart and you’ll be free to roam the waters—the last thing salty dogs want is to be leashed.