1. Explore a national park
The United States has 61 National Parks, including the most popular ones: the Great Smoky Mountains, the Grand Canyon, Rocky Mountain, Zion, Yellowstone and Yosemite.
Each spot has its own unique natural beauty and geography — from dusty deserts to majestic waterfalls, towering mountain ranges and volcanoes. There are also more than a thousand scenic and historic trails across the country ready for your trekking pleasure.
Seniors can purchase a lifetime pass that covers entrance fees to more than 2,000 federal recreation sites, including national parks, wildlife refuges, grasslands and more.
The lifetime ticket costs $80 (plus $10 shipping), while a simple annual pass for seniors costs $20.
2. Set sail on a cruise
Cruises offer a perfect mix of comfort and sightseeing, shopping and island hopping.
If you don't want to venture too far from the U.S., Carnival Cruises runs seven-night cruises around the Caribbean starting at $400 per person, boarding in Miami, Tampa, and Port Canaveral in Florida and in Houston and Galveston in Texas.
Norwegian Cruises offers lots of options, like a 10-night cruise of the Greek Islands and Italy for just $899 per person or a seven-night western Mediterranean cruise for $829 per person.
When budgeting your trip, make sure to add the cost of airfare and day excursions.
3. Go on safari
A trip to sub-Saharan Africa is perfect for retirees looking to discover amazing wildlife.
Travel site Kayak shows you can find round trips to South Africa or Botswana from either New York or Washington, D.C., for under $1,000. From Chicago, there are flights in that same price range to Tanzania.
A seven-day safari experience in Tanzania goes for $2,350 per person.
In Cape Town, South Africa, you can see all of the "Big Five" (lion, leopard, rhino, elephant and African buffalo) via a one-day safari for $190 per person or a three-day safari including guided 4x4 game drives and meals for $362 per person.
4. Chase your passions
With hundreds of festivals going on all year-round, you’ll find one dedicated to every passion under the sun.
If you're into Shakespeare, then Ashland, Oregon, has a festival dedicated to the Bard. Tickets cost $49 to $155 per poetic production.
Free celebrations of art abound — like the unique Canal Convergence fest in Scottsdale, Arizona, attracting thousands of visitors each year.
For music fans, must-do festivals include Outside Lands in San Francisco ($155 per day); Grand Point North in Burlington, Vermont ($84 for two days); and the Austin City Limits Music Festival in Texas ($105 for a one-day ticket).
5. Go sailing
You can sail around just a corner of the world, or the entire thing — and it's more affordable than you think.
Explore the Find A Crew or SailOpo websites, which connect prospective crew members with boat owners. You can sail for free or even get paid to contribute your skills on board.
Or, you can join a boat share club. Complete a basic sailing certification, pay the membership fee (which can be as low as $35 per month), then pay to book your boat for a day.
And don’t forget to check with local yacht clubs — they’re always looking for crew members for casual summer races.
6. Escape to an island paradise
Islands offer a wide variety of historical ruins, wildlife and climates to enjoy, no matter what your retirement budget.
The Galapagos Islands off the coast of Ecuador could be your next adventure. Tourists can stay on several of the islands without booking a guided tour and enjoy free access to the Galapagos' unique flora and fauna, say budget travelers at Thrifty Nomads.
Snorkeling costs $15 to $20 for the gear, and sea lion selfies are free — on any beach where those creatures hang out.
7. Rent a castle
Celebrate your freedom from the daily grind by literally living like royalty for a week.
For less than $200 per night, you can rent a tower with a rooftop patio in the privately owned Drummond Castle in Drogheda, Ireland.
Or, stay for under $400 per night at Kilcolgan Castle near Galway and enjoy easy access to the famed (but risky) Cliffs of Moher for day trips.
To rent an entire castle, take a look at Tudor Manor House in Somerset, England. Comfortably-sized for 22 people, you can rent the whole chateau for about $3,400 for two nights or around $12,000 for a whole week.
8. Visit a natural wonderland
While the Galapagos are rather remote, you can see amazing wildlife closer to home, in Costa Rica. The Central American nation is home to over 500,000 species of plants and animals.
Costa Rica is inexpensive, and you can save even more by avoiding all-inclusive tours, eating local meals and making your own itinerary.
In Tortuguero National Park on Costa Rica’s north coast, you'll see endangered green turtles, monkeys, crocodiles, sloths and more. For $40 to $60, you can enjoy a boat or kayak tour through it all.
At the Monteverde Cloud Forest, you can walk through the tree canopy, visit a coffee plantation and butterfly gardens — or just enjoy hiking and wildlife spotting in the park.
9. Go road tripping
You don't have to get on a plane to experience a once-in-a-lifetime adventure. Take a great American road trip instead.
Drive the iconic Route 66 — or go off the beaten path along the Columbia River Scenic Highway in Oregon, or the Million Dollar Highway in Colorado, which runs between two historic mining towns.
Road trips are perfect aboard an RV, or you can stay at a selection of bed and breakfasts along the way.
Taking route 66 from Chicago to Los Angeles would cost $225 for gas one way, and midrange lodging would add about $1,670, says Money. You'd also want to budget for food and entertainment along the way.
10. Toast to your retirement
Toast your retirement with a tasting tour through a fabulous wine country at home or abroad.
To experience old-world wine in Burgundy, France, travel to Beaune and take a half or full-day bicycle and wine tasting tour starting at under $100 per person.
Stateside, Walla Walla, Washington, is just bursting with wineries. For the VIP experience, Imbibe Wine Tours will take two to six people on a five-hour drive through the region for $510.
Just a few hours’ drive or a short flight from the East Coast, the Niagara region of Canada and the U.S. is home to more than 100 wineries. There's even a dedicated Niagara USA Wine Festival every summer in the village of Lewiston, New York.
11. See the northern lights
The magnificent lights of the aurora borealis are visible around the world, from the sea islands in Denmark to Canada, Finland, Iceland, northern Scotland — and of course, in Alaska.
Visitors to the 49th state can check out the northern lights and take a tour of Chena Hot Springs, leaving from Fairbanks.
For less than $200 per person, you can see the awe-inspiring lights, visit the Aurora Ice Museum and enjoy a soak in the hot mineral springs.
12. See the great wonders of the world
The ancient and modern wonders of the world are among the most awe-inspiring endeavors ever built.
The Seven Wonders of the Modern World include the Great Wall of China, the city of Petra in Jordan, the Colosseum in Rome, Chichen Itza in Mexico, Machu Picchu in Peru, the gigantic Christ the Redeemer in Brazil and the Taj Mahal in India.
If you'd like to start with a visit to the Chichen Itza pyramid, round-trip flights to Cancun, Mexico, are cheap. Prices range from about $200 from Chicago, New York and Houston to $412 and up from Salt Lake City.
A private bus to Chichen Itza your Cancun hotel starts around $65 per person. Then, a private tour of the site costs $50 — or you can just enjoy it on your own.
13. Get romantic in Europe
Retirement can be a great opportunity to reconnect as a couple — and a romantic trip to Europe is more affordable than ever.
For the best deals, avoid visiting during the high season, between the end of April and mid-September.
Round-trip flights to Barcelona can be booked for around $400 from New York and about $700 from Kansas City, Kayak shows. Round trips to Paris from New York start at $325 or less than $700 out of Kansas City.
Off the beaten path, check out the castles of Dubrovnik in Croatia and enjoy the city's gorgeous beaches and budget-friendly fine dining. Round-trip flights start at about $600 from New York and can be found for under $900 from Kansas City.
14. Discover your heritage
You consider yourself a history buff, but have you ever visited your family's country of origin?
Now that you're retired, it's the perfect time to research your roots and maybe even visit the place of your heritage.
There's nothing quite as awe-inspiring as walking into a tiny village on the other side of the world and meeting long-lost relatives, seeing your family's ancient crest on a castle, or finding your last name on a street sign.
Not sure where to start? Go to FamilySearch.org and type in your family name and country of origin. Prepare to be wowed by the connections you find.
15. Go on a local adventure
We often forget all the fantastic things we haven't tried that are right on our doorsteps.
Now that you have plenty of time on your hands, make a point to take in local restaurants, bars, museums, and events you've never tried before. You'll be surprised at all the unique things home has to offer — when you just stop and take a look.
The Local Adventurer blog and Lonely Planet's American travel page can give you ideas on where to get started.
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