It's still hard to believe that many baby boomers, the generation that typified the eternal youth of the 1960s, are officially senior citizens. Three years ago, the first batch of boomers turned 65, ready to cash in on Social Security, their IRAs, and other savings and retirement accounts.

Those aren't the only perks you're entitled to if you've recently passed the senior threshold. There are a host of discounts and deals you might qualify for, especially when it comes to traveling. If you're acquainted with snowbirding (off-season vacationing) and you live in an empty nest, now is the perfect time to plan your next fall trip.

We've researched five fall vacation ideas that are not only affordable, but will keep you active, as well.

Cheap Vacation Ideas for Baby Boomers

1. Educational Trips

These cheap vacation packages include going back to school -- sort of. These tours give you the chance to go beyond sightseeing.

"Programs enable you to take a more in-depth view of destinations, by offering off the beaten track and behind the scenes views through connections with educators and local insiders," reports USA Today.

Road Scholar is one not-for-profit provider of educational tours available across the country. Some of the coast-to-coast options through Road Scholar include a South Carolina riverboat cruise and a five night New York City experience visiting several Manhattan attractions.

Then there's Senior Summer School, where Boomers can enjoy weeks-long tours of historic locations in Madison, Wis., Colorado Springs, Colo., and other parts of the country steeped in history.

2. White Mountains, NH

The best cheap vacation spots are also the ones that provide natural beauty, bucolic scenery and a chance for discovery. The northern portion of the Appalachian Trail in New Hampshire, ending in the White Mountains, is one such place.

According to Michael Schuman of Grandparents.com, there are camps specifically designed for the 50-plus crowd as part of the Appalachian Mountain Club's Highland Lodge, where five-night stays are scheduled year round, perfect for an autumnal or winter hiking excursion.

"The woods are yours whether you prefer snowshoeing and skiing or vigorous hiking, leisurely walking, or expert guided tours of the area's natural history," Schuman wrote.

3. Costa Maya, Mexico

If Harrison Ford could play Indiana Jones when he was pushing 70, boomers can unearth their hidden adventurer with another of these cheap vacation deals: a venture into the exotic surroundings of Othon P. Blanco, south of the border.

"If your interpretation of cultural tourism means ancient Mayan ruins and modern Mayan fishing villages rather than pulsing nightlife at a club named for an amphibian, this is the destination for you," Schuman wrote. Here you could do everything from lean against ancient Mayan pyramids to gaze at the native fauna and flora -- vine swinging, zip lining and scavenging for ancient artifacts are optional.

4. Portland, OR

Yes, there's Las Vegas. There's Miami. There's Los Angeles. You've heard about (and probably visited) all the same tourist traps decades over. Have you considered Portland? For those boomers who've always kept the spirit of the '60s alive, Portland -- arguably the Pacific Northwest's progressive, green capital -- is an ideal vacation spot for seniors who are frugal, environmental and artistic.

"Portland values creativity and treasures such traditions as its 105-year-old Rose Festival held each June," wrote Christine Delsol for AARP. "Year-round, free activities abound, and hotel and restaurant prices are low by urban standards. So is the tab for the craft beer served in the city's 40-plus microbreweries."

5. Volunteer Vacations

A weekend at a random resort is just that -- only a weekend. Volunteering lasts for a lifetime and comes with the knowledge that you've played a direct, active part in helping others less fortunate.

Such is the aim of the affordable vacation packages called "volunteer vacations," which "offer travelers the chance to get below the surface of a destination and have meaningful interactions with the local people," said Molly Feltner of SmarterTravel.com.

Interested in teaching English? Working with the homeless? Aiding environmental cleanup efforts? Services like Global Volunteers (where more than 60 percent of participants are older than 50), Elderhostel (which offers senior volunteer programs) and i-to-i Travel & Adventure (which leads 300-plus projects in more than 24 countries) range in price from several hundred to a few thousand dollars -- a nominal fee for priceless outcomes that make a difference.

This fall, you shouldn't rule out trips to Disney World with the grandchildren, a chartered cruise to the Caribbean or island hopping in Hawaii. You can even plan a staycation! But by taking advantage of some of the low-to-no-cost vacations on this list, you'll be able to better save money for a more lush family vacation while getting the most out of your adventurous -- and affordable -- side.