An azimuth compass is a nautical instrument used to measure the magnetic azimuth, the angle of the arc on the horizon between the direction of the Sun or some other celestial object and the magnetic north. This can be compared to the true azimuth obtained by astronomical observation to determine the magnetic declination, the amount by which the reading of a ship's compass must be adjusted to obtain an accurate reading. Azimuth compasses were important in the period before development of the reliable chronometers needed to determine a vessel's exact position from astronomical observations.

HMS Resolution was a sloop of the Royal Navy, a converted merchant collier purchased by the Navy and adapted, in which Captain James Cook made his second and third voyages of exploration in the Pacific. She impressed him enough that he called her "the ship of my choice", and "the fittest for service of any I have seen".