(MONEY Magazine) – If you have time off coming, and the prospect of pina coladas on the beach fills you with dread, you might want to consider an educational vacation. Your options include anything from a seal-watching jaunt in Canada to an archaeological dig in Jerusalem to a weeklong art history course at Cornell University in Ithaca, N.Y. . Costs vary as much as the trips themselves and depend on accommodations. A weeklong Cornell program, for example, costs $585 per person, including tuition, room and board. For a listing and brief description of about 250 adult educational sojourns, check out the just-released sixth edition of Learning Vacations by Gerson G. Eisenberg (Peterson's, $11.95). Another useful source: The New World of Travel 1990 by Arthur Frommer (Prentice Hall, $16.95), available in March. And if you're really looking to roll up your sleeves for an ''un-vacation,'' telephone Earthwatch (617-926-8200), a not-for-profit organization in Watertown, Mass. By signing up for one of its two- to three-week expeditions, you can assist scientists studying kangaroos in Australia or digging for mammoth bones in South Dakota. Costs, which may be considered tax-deductible contributions, range from $800 to $2,000; after the federal tax subsidy is figured in, the real cost to you can be a third less. For similar projects, consult Volunteer Vacations by Bill McMillon (Chicago Review Press, $11.95). -- B.K.