Solo travelers must be at least 18 years old to book a tour. The 18-to-Thirty-Something Tours are designed for travelers 18 to 39 years age. Family adventures are recommended for families with children, 6 to 17 years old. However, children at least 12 years of age can take the standard tours when accompanied by an adult (2 children per adult.) The 2-adult restriction is not enforced for G Adventures' Family Adventures.