COSTA RICA
Rock of Ages
Visit the mysterious, nearly perfect stone spheres that have been found along Costa Rica's southern Pacific coast with Adrian Bonilla, the Palmar Sur site's lead archaeologist, at a location that is accessible only with permission from the community. Hundreds of these spheres, known locally as Las Bolas and ranging in size from bowling balls to 15-ton boulders, have been discovered since the 1940s; Bonilla, who works for the National Museum in San José, found the most recent one a year ago while excavating the remains of a pre-Columbian village. Though early theories speculated that the stones were carved by aliens or by Mother Nature, Bonilla believes they are the work of the native Chiriqui people. Cost: $2,000, including a donation to the project. Source: Richard Edwards, Green Spot Travel (877-891-3539; richard@greenspottravel.org; greenspot.travel). BEST FOR: Amateur archaeologists and conspiracy theorists looking for the straight story. BUT BEWARE: Don't come in September and October, when the rains are so heavy that your charter flight to the site might not even be able to take off.

HAWAII
Seeing Stars
'Imiloa Astronomy Center can arrange for a handful of individuals or couples a year to visit the Mauna Kea Observatories, accompanied by an astronomer. A tax-deductible contribution is requested. Contact Gloria Chun Hoo at 'Imiloa for details (808-969-9705).

ASIA/PACIFIC

AUSTRALIA
Aboriginal Artifacts
Take a private tour of Adelaide's South Australian Museum, which has the most comprehensive collection of Australian Aboriginal artifacts—as well as the best opalized fossil collection—in the world. The museum's indigenous-culture expert will show you around, and you'll also visit an off-site warehouse full of items, including thousands of boomerangs and spears from across Australia. Finally, you'll stop at Marshall Arts, a gallery that specializes in contemporary Aboriginal pieces. Cost: $1,415, including lunch. Source: Drew Kluska, Outback Encounter (61-8-8354-4405; dkluska@outbackencounter.com; outbackencounter.com). BEST FOR: Those who don't have the time for a trip into the Outback but who want a taste of Aboriginal life. BUT BEWARE: Gazing at stack after stack of artifacts can be overwhelming if you don't have at least a passing knowledge of (or a passion for) the culture.

CHINA
Challenge a Champion
Play table tennis with Zhang Yining, the current women's team and singles Olympic champion. You'll spend 60 to 90 minutes playing a few rounds, with time for photo ops and a chat about her Olympic experience. Your visit will include a tour of the facility where Olympic badminton and martial arts hopefuls also train, and the chance to meet and speak with the center's staff and coaches. Cost: $16,500; also available is a similar experience with Wang Tao, the '92 Barcelona Olympics doubles champion, for $9,800, and a two-hour lesson with Wang Tao's former coach for $500. Source: Guy Rubin, Imperial Tours (888-888-1970; guy@imperialtours.net; imperialtours.net). BEST FOR: Those who want bragging rights—how many people can claim to have played an Olympic champion? BUT BEWARE: Because of her rigorous training schedule, Zhang Yining has limited availability January through September.