- Celestial Navigation: Ancient mariners used the positions of the sun, moon, and stars to determine their location and course. The simplest technique was to observe the position of the North Star (Polaris), which always remains in the same location in the night sky. More advanced techniques involved measuring the angles between celestial bodies and the horizon.
- Compasses: The magnetic compass, which allows sailors to determine the direction of true north, was first invented in China during the Song dynasty (11th-13th centuries) and later adopted by European sailors in the 14th century.
- Astrolabe: The astrolabe was an important navigational tool used from ancient times to the Renaissance. It allowed sailors to determine their latitude and longitude by measuring the angles between the sun and the horizon. The astrolabe also incorporated features for measuring the altitude of celestial bodies and calculating the time of day.
- Quadrant: Similar to the astrolabe, the quadrant was another instrument used to measure angles between the horizon and celestial bodies. It consisted of a quarter-circle arc with a plumb bob suspended from its center.
- Lead and Line: Sailors used a heavy weight attached to a rope (the lead) to measure the depth of the water. This information helped them avoid shallow areas and rocks.
- Charts and Maps: While detailed sea charts did not become widely available until the 16th century, ancient sailors did use simpler maps and charts to aid in navigation. These charts often depicted coastlines, landmarks, and hazards.