What tool is commonly used for determining a ship's position at sea?

The Global Positioning System (GPS) is widely regarded as the most reliable and precise tool for determining a ship's position at sea. GPS utilizes a network of satellites to triangulate a vessel's exact geographical location based on signals received from multiple satellites. This method provides accurate readings in real-time, allowing sailors to navigate effectively and safely.

While a compass is essential for indicating direction relative to magnetic north, it does not provide specific positional information. Radar is valuable for detecting other vessels and landforms, particularly in low visibility conditions, but it requires interpretation and does not directly indicate a ship's position. A depth sounder helps in measuring water depth but is not used for determining position on a global scale. Therefore, GPS stands out as the most comprehensive tool for maritime navigation by offering precise location coordinates, which are crucial for safe and efficient travel at sea.