Gilolo, Or Halmahora, an island of the Indian archipelago, in the Molucca group, between Celebes and New Guinea, separated from the former by the Molucca passage and from the latter by Gilolo strait; area, about 5,780 sq. m.; pop. estimated at 27,000. It is crossed by the equator, and lies between lat. 2° 30' N. and 1° S., and Ion. 127° and 129° E. The outline somewhat resembles that of Celebes. The island consists of four peninsulas radiating from a centre situated in about lat. 0° 40' N. Of these peninsulas two trend N. and S. respectively, along or near the 128th meridian; one extends toward the N. E.; and the fourth stretches to the S. E., terminating in Cape Tabo, the most easterly point of the island. The length of Gilolo is nearly 250 m. The range of smaller islands to which the name Moluccas was originally applied, including Ternate, Tidore, Morty, Makian, and Batchian, skirts the southerly part of the W. coast. Gilolo is of volcanic formation. From the sea coast, which is itself described as in many parts mountainous, lofty mountains are visible in the interior, some of which are said to be volcanoes.

According to Wallace, the surface seems to have undergone changes of elevation within a recent period; and the upheaval of a mountain at Gamakonora in the northern peninsula is reported to have occurred in 1673. Fringes of coral reef interfere with navigation along many portions of the coast. The inland regions are but very slightly known; they appear to consist largely of elevated tracts of forest. The clove tree is indigenous to the island. About four fifths of the inhabitants are ruled by the sultan of Ternate, whose residence was formerly at the town of Gilolo, on the W. coast of the northern peninsula. The Malay element predominates, but the active and energetic inhabitants of the northern peninsula belong to an indigenous race called Alfuros, differing both from the Malays and the Papuans, yet possessing some of the characteristics of each. The government of the Netherlands maintains an insignificant military station at Dodingo, a village opposite Ternate. The principal products of Gilolo are sage, spices, tortoise shell, and tropical fruits.