It’s easy to forget that Manhattan is an island, but there’s water all around us. This means there are plenty of opportunities for an oft-overlooked summer sport: paddling, either in a kayak or a canoe.

With summer approaching, there’s no better time to get out of the gym and into the fresh air. Brisk paddling can burn as many as 400 calories an hour, and spending time outdoors is a proven stress-reliever. It’s also a good choice for those concerned about pounding their joints on pavement or hard running trails. “Paddling is no-impact,” said Danilo Bonilla, a 12-year kayaking veteran and manager of the Manhattan Kayak Company. “There’s very little risk of injury.”

Kayaking (and its cousin sport, canoeing) is usually considered an upper-body workout, but Mr. Bonilla says that true kayaking technique involves the entire body. “We teach people to use their whole torso and legs to move the boat, not just their arms.”

New York City’s canoe and kayak clubs have programs and trips for paddlers of all levels, and, best of all, many clubs’ walk-up programs are free or inexpensive. Because the summer season can be busy, it’s a good idea to call ahead and double-check departure times and trip size limits. Paddling clubs provide basic equipment and flotation devices, but you should also confirm any requirements for attire.

The New York City Downtown Boathouse (646-613-0375, www.downtownboathouse.org), offers walk-up kayaking on the Hudson River every weekend and holiday from May 15 through October 15. Boats depart from three locations (Pier 26 in TriBeCa, Pier 66A in Chelsea, and 72nd Street in Riverside Park); walk-up trips and Wednesday-night instructional classes are always free. Walk-up trips are only 20-minutes long, but equipment and basic instruction are provided at no charge. The only requirement is that you know how to swim, although paddlers stay inside protected embayments, away from fast currents and rough water.

After participating in a few casual walk-up trips, paddlers are eligible for the Downtown Boathouse’s three-hour guided trips into the Hudson proper. Departing every weekend morning from Pier 26, these four- to five-mile tours are very popular – plan on arriving by 7:45 a.m. to sign up for a boat. Departure time is 8 a.m. sharp.

The Inwood Canoe Club (212-463-7740, www.inwoodcanoeclub.org), founded in 1902, is New York’s oldest canoe and kayak club. The Inwood boathouse, steps from the Dyckman Street Marina in Fort Washington Park, sends kayakers into the upper Hudson every Sunday from May 22 through the end of September. There’s no cost, and paddlers can stop by any time between 10 a.m. and 1 p.m. to take advantage of this beautiful stretch of the Hudson, which is famous for its views of the George Washington Bridge. The Inwood Club also organizes competitive kayak teams for those who would like to take the sport a little more seriously.

If you’re willing to spend some money to improve your kayaking technique, the Manhattan Kayak Company (212-924-1788, www.manhattankayak.com), one block north of Chelsea Piers, offers dozens of classes for beginners and pros alike. Start with Paddle Basics, a comprehensive four-hour course that begins with land drills before moving to the water. The cost is $160, or $128 for Chelsea Piers members. Private instruction is also available for $100 an hour (two-hour minimum for the first session).

In addition to class instruction, the Manhattan Kayak Company offers a variety of group tours. Beginners’ trips average $55 a person and usually last about 90 minutes. The Sunset Tour lets participants watch the sun go down over the city; the weekend Brunch Tour winds up in Chelsea for post-paddle eating.

Advanced tours cost $200 to $250 a person and include trips to Coney Island, Riker’s Island, and the Verrazano Narrows Bridge. These are designed for the dedicated and physically fit – you’ll spend almost an entire day paddling.

For an intermediate challenge, the company runs trips to the 79th Street Boat Basin ($75 a person), Governor’s Island ($100 a person), and Red Hook ($150 a person). There’s also a trip that takes paddlers to the Statue of Liberty for a new perspective on a familiar landmark – though, as the company’s Website notes, full circumnavigation of the statue will depend on wind and current conditions ($100 a person).

For most New Yorkers, the two-mile Gowanus Canal is an infamously stinky waterway, not a pleasant place to paddle. Many steps have been taken to correct this view in recent years, including a $270,000 state redevelopment allocation to the Gowanus Canal Community Development Corporation and a number of successful cleanup projects.

The Gowanus Dredgers Canoe Club (718-243-0849, www.gowanuscanal.org), founded in 1999, is determined to revitalize the canal by “reconnecting the community with their shoreline” and promoting stewardship of its waters. “I’d advise against drinking it,” said Owen Foote, the Dredgers’ treasurer, who’s been paddling the canal for six years. “We also tell people to wash their hands after using canoe equipment, but it’s just as safe as using public restrooms.”

The Dredgers offer free walk-up canoe trips along the canal and in the Red Hook Estuary, departing from Gowanus (2nd Street near Bond Street) and Red Hook (Louis Valentino Jr. Pier, near Coffey Street). Other Dredgers-sponsored events include trips to Governor’s Island, a Revolutionary War history trip, and an Oktoberfest boat race.

“Our programs are definitely geared toward beginners,” said Mr. Foote, who also noted that “the rust that lines much of the shoreline reminds us of our mortality and the fact that nature needs to be respected.”

Farther south in Brooklyn, Canarsie’s Sebago Canoe Club (718-241-3683, www.sebagocanoeclub.org), runs an Open Paddle kayak program on Jamaica Bay on Wednesdays at 5:30 p.m. and Saturdays at 9:15 a.m. Some trips feature guest speakers who discuss the bay and its ecosystems. Trips are limited to 15 participants on a first-come, first-served basis, and there’s a $10 fee to cover insurance. The club is at 1400 Paedergat Avenue North, on Paerdegat Basin at the end of Avenue N.