Howland Island is an uninhabited coral island located just north of the equator in the central Pacific Ocean, about 1,700 nautical miles (3,100 km) southwest of Honolulu. The island lies almost halfway between Hawaii and Australia and is an unorganized, unincorporated territory of the United States. Together with Baker Island it forms part of the Phoenix Islands. For statistical purposes, Howland is grouped as one of the United States Minor Outlying Islands. The island has an elongated cucumber-shape on a north–south axis, 1.40 by 0.55 miles, and covers 1 square mile.

Guano is the accumulated excrement of seabirds or bats. Guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a lesser extent, sought for the production of gunpowder and other explosive materials.