Thousands of public-spirited and adventurous travelers, among them former President Jimmy Carter, are signing up for worthwhile endeavors that aid individuals and institutions in America and abroad.

Sponsoring organizations across the globe seek willing bodies of all ages as well as skilled professionals to sign up for short-term volunteer stints.

Whatever your interest — environmental, health, archaeological, socio-economic, cultural, scientific or educational — there's a need for your assistance. If you crave stimulation and activity, and a sense of personal accomplishment, you are a likely candidate for a volunteer vacation.

Opportunities to travel (often on the cheap) while making small but significant contributions to the welfare, preservation and knowledge of our planet are practically boundless. Among hundreds of examples, you could choose to track whale populations off Baja, excavate Norse settlements in the Scottish Isles, work on reforestation in Oregon, record oral histories of clansmen in Papua New Guinea, study fragile reef ecosystems in Belize, or help operate a medical clinic in Uganda.

Programs to pick from include using computers to reconstruct prehistoric villages in Turkey, teaching English to rural school children in Russia, observing the social structure of elephant herds in Botswana and conserving damaged art treasures in Italy. And the truly adventurous could join an expeditionary research voyage in the Arctic.

The nature, scope and personnel requirements of volunteer projects vary from one non-profit organization to the next. Usually, travelers may volunteer their services for anywhere from one week up to a year, depending on the time frame for completion of a particular project. Some organizations welcome the talents and enthusiasm of inexperienced but trainable volunteers, while others may seek the assistance of volunteers with specific skills, such as physicians, agronomists or engineers. Each sponsor will provide applications, information on volunteer needs and project opportunities as well as details on costs, clothing and any personal equipment that the prospective participant must supply.

Singles, couples and sometimes families (children 8 and older) are accepted as volunteers. Studies indicate that more than 40 percent of volunteers on field expeditions and special projects are older than 40. Mature folks who may have missed a youthful stint in the Peace Corps are signing on for short-term commitments at work camps, archaeological digs, village schools, hospitals and construction sites. Volunteerism, which used to be the exclusive province of students, has come into its own as a highly rewarding travel experience for all ages.

Some projects, particularly the ones that extend over many months, will require only an expenditure for transportation to the site, with the sponsor providing bed and board and a small stipend. Other sponsors expect the volunteer participant to pay for air flights and nominal costs of food and lodging. Accommodations could range from shared field tents or dormitories, to simple inns or even semi-luxurious hotels. Bed and board arranged by sponsors is generally cheap and affordable even to those on the tightest budgets.

For those projects where the sponsor does not pay for meals and accommodations, the program fee for a volunteer vacation could range from $50 to $3,000-plus, depending on the project's duration, an agency's degree of involvement and the standard of bed and board provided.

Volunteer vacations offer an added bonus: many of your charitable-work expenses may be tax-deductible.

Irene Croft Jr. of Kailua, Kona, is a travel writer and 40-year veteran globetrotter. Her column is published in this section every other week.