Cape Cod is known all over the world for its majestic beaches that hug the Atlantic coastline, and a relaxing day stretched out on the sand is the first order of business for many vacationers to this destination.

But if you crave a little adventure to break up even the most blissful of beach days, you can find it without even straying from the ocean. Here’s how:

Cruises and Eco-Tours
Barnstable Harbor Eco-Tours offers interactive tours known as Sandbar Explorations that are geared toward families. Expert guides point out countless species of sea creatures— from spider crabs and moon snails to ice cream cone worms—as they traverse the multiple sandbars of Barnstable Harbor.

Sandwich-based Cape Cod Learning Tours offers private walks along kettle holes, salt marshes and tidal flats. The hands-on guided experience has families wading into local waters in search of lobsters, crabs, sea urchins and other marine critters. The tours tend to be half-day and daylong treks— complete with a picnic lunch—that are tailored to a family’s particular interests.

Hy-Line Cruises offers sightseeing cruises along the legendary Cape Cod Canal. Travelers on board learn the compelling history of the historic canal and hear intriguing anecdotes about some of the fascinating places along the way, including Aptucxet Trading Post, Grey Gables and Massachusetts Maritime Academy. Specialty cruises feature sunset cocktails and live music.

For a unique land and sea adventure, climb aboard Cape Cod Duckmobiles, a refurbished military amphibious vehicle that will take you on a narrated cruise by historic landmarks in downtown Hyannis and through scenic Hyannis Harbor (please note: quacking is required of passengers).

Kayaking
Gliding along the water in a kayak is a peaceful way to get out and experience Cape Cod’s coastline. Great Marsh Kayak Tours provides a range of tours for both experienced and first-time kayakers. One of the most appealing is the three-hour Sunset Spectacular, where you’ll paddle along Cape Cod Bay as the sun prepares to slip under the horizon.

Cape Kayaking conducts tours in and around the Cape Cod National Seashore; popular tours include Nauset Marsh at High Tide, Monomoy Island and Clamming—where you’ll forage for your dinner in the mud flats and sandbars of Nauset Estuary. Meanwhile, Cape Cod Kayak offers tours in and around Upper Cape waterways; Quissett Harbor, Monks Cove and Scorton Creek are just a few of the scenic spots you'll explore.

Venture Athletics Water Sports and Flyer’s Boat Rental in Provincetown, along with Cape Cod Watersports at the Bourne Bridge, offer kayak rentals if you’re interested in heading out on the water solo to create an experience all your own.

SUP
Not only is stand-up paddle boarding a fantastic workout, it’s a cool opportunity to observe the local waters from a different vantage point. Adventure Chatham has the largest rental fleet of stand-up paddle boards on Cape Cod. The experienced staff is equipped to lead group and private lessons, as well as guided tours around the area’s serene local ponds and saltwater spots.

Anywheresup.com is a local company that offers paddle board rentals, as well as a rent-to-own your own paddle board program. MOCEAN in Mashpee Commons offers rentals and weekly classes to polish your paddle board skills, while Stand Up & Paddle Cape Cod offers rentals, private lessons and guided tours (including a special Shellfishing SUP). Sickday Surf Shop in Wellfleet also offers SUP rentals, and a full line of apparel and accessories to look like a pro doing it.

And in East Sandwich, the folks at RideAway Adventures Cape Cod have great skills; instructors lead a week-long popular Kids Adventure Camp at New Seabury Marina, where youngsters learn paddle boarding basics in a fun, engaging setting.

Seal Tour
While you might see seals frolicking in the distance from the shore, nothing beats a boat cruise devoted to watching the friendly sea creatures. On a boat out of Orleans, Blue Claw Boat Tours offers the chance to observe seals swimming and playing in their natural habitat, while the captain on board shares insight on local landmarks and lore along the way. The Harwich-based operation Monomoy Island Excursions (monomoysealcruise.com) offers boat tours to Monomoy, a barrier island where thousands of harbor and gray seals make their home. The Monomoy Island Ferry also offers seal cruises to the island.

With Beachcomber Boat Tours, guests are transported by trolley to the boat’s location at Ryder’s Cove, and then cruise Pleasant Bay in search of seals along the Chatham Harbor waterways.

Whale Watching
Whale watching is another exciting ocean adventure, with trips running from mid-April through October. Stellwagen Bank National Marine Sanctuary off Cape Cod consistently ranks among the top 10 places on the planet to see these majestic creatures; sightings could include anything from Humpback, Finback, Minke and Pilot whales to dolphins, porpoises and seals. Led by expert naturalists aboard comfortable vessels, threeto- four-hour trips depart in season from Provincetown Harbor (Dolphin Fleet Whale Watch) Barnstable Harbor (Hyannis Whale Watcher Cruises) and Plymouth Harbor (Capt. John Boats —also now operating out of MacMillan Wharf in Provincetown).

Not to be missed is the new Cape Rib Tours out of Hyannis, which ventures out to see the world’s largest mammals with a smaller, more intimate group; at 1,000 horsepower, this is the fastest whale watch boat on the Cape.

Charter Fishing Excursions
For lots of folks, there’s not a more enjoyable way to engage with the sea than by tossing in a line and waiting for the fish to bite. The Cape has a slew of top-notch charter boats that offer the chance to fish on the open ocean for a few hours or longer. Out of Harwich Port, Yankee Deep Sea Fishing offers morning and afternoon excursions for scup, black sea bass, fluke and tautog aboard the 62-foot Yankee ll vessel. Hy-Line Fishing offers bottom fishing trips, as well as cruises where passengers can troll for sea bass, blues or stripers.

Hyannis-based Helen H has a five-boat fleet that ranges from a 100-foot party boat to a 30-foot Sea Hawk, catering to a variety of fishing excursions. And striped bass, tuna and sharks could be the catch of the day aboard Magellan Fishing Charters, departing out of Saquatucket Harbor in Harwich Pot.