How to Make a Holiday Out of Helping Others : So-called ‘volunteer vacations’ ask participants to donate their skills in spots around the world.

Teaching children math or computer skills in a village in Java . . . helping Polish farm children learn English . . . helping to construct low-cost homes for needy families in the South . . . renovating school buildings in Jamaica . . . sitting on a riverboat in a wilderness area of the Amazon, listening to dolphins.

Those are some of the new offerings from Elderhostel, the Boston-based nonprofit organization that offers thousands of educational and travel programs for adults age 60 and over throughout the United States and abroad. An increasing number of seniors have found such volunteer work both challenging and satisfying.

Though the aforementioned “volunteer vacations” are part of Elderhostel’s 1993 experimental Service Programs, they are not entirely new.

All have previously served as projects of such nonprofit service organizations as Habitat for Humanity International, Global Volunteers and Oceanic Society Expeditions. Elderhostel’s participation just opens them to a far larger audience of travelers.

Some examples:

* A three-week “volunteer vacation” in Jeruk Legi, a tropical village on the southern coast of Java, Indonesia. Travelers live in dorms while teaching junior and senior high school students English, science, math and computer skills, and perhaps--depending on individual skills and expertise--helping out with other needed school projects such as building repair and construction. Cost: $2,976 per person, including round-trip air fare from Los Angeles.

* Two weeks helping to construct low-cost homes for needy families in small, disadvantaged communities such as Americus, Ga.; Coahoma, Miss., and Phelps, Ky. Work ranges from digging and carpentry to wiring and painting. Cost: $781, which includes modest accommodations and meals, but not transportation. This is the program with which former President Jimmy Carter is involved.

* Two weeks on a 76-foot research/excursion vessel sailing out of Iquitos, Peru, up the Amazon River to a remote area, to study the boto (pink) river dolphins to help protect them from encroaching development. Cost: $2,861, including round-trip air fare from Miami.

* Two weeks in Happy Grove, Jamaica, 24 miles south of Port Antonio, teaching, gardening in school plots, helping to renovate hurricane-damaged buildings and other projects. The program tries to utilize individual skills of travelers, whether in construction, nursing, health care, etc. Cottage accommodations, simple local meals. Cost: $1,263, not including transportation to Jamaica.

* A week studying dolphins, whales and other marine mammals in Monterey Bay, Calif., staying ashore in a Monterey Peninsula lodge, and participating in daily research trips on a 55-foot motor vessel. Cost: $1,014, not including transportation to Monterey.

Elderhostel’s new 12-page Service Program booklet includes details of each volunteer vacation, along with dates (most extend through September). Well aware of the departure from its usual university-based educational programs, Elderhostel clearly spells out the most important detail up front: These programs are not for everyone.

The service programs are for adults age 60 and over, and a spouse or companion at least 50 years old. The spouse or companion is expected to be a full participant in the program.

The possibilities of tax deductions for participation in these programs is explained. Health considerations, insurance, travel arrangements and other subjects are also covered.

For more information, write Service Programs, Elderhostel, Box 1751, Wakefield, Mass. 02135, or call (617) 426-8056. For information on its general educational programs in the United States and Canada, write Elderhostel, 75 Federal St., Boston, Mass. 02110-1941, or call the preceding number.