Computer simulations have demonstrated the high accuracy of the sunstone, a navigational tool used by Viking sailors. The sunstone, also known as a sun compass or sky compass, consists of a transparent crystal, such as calcite or cordierite, with a small hole drilled through it. When the sunstone is held up to the sky, the hole acts as a pinhole camera, projecting an image of the sun onto the crystal's surface. The position of the sun's image can then be used to determine the direction of the sun, and thus the cardinal directions.

Computer simulations have shown that the sunstone can be used to determine the position of the sun with an accuracy of within a few degrees. This level of accuracy is sufficient for navigation purposes, as it allows sailors to determine their general direction and stay on course. The sunstone was likely used by Viking sailors in conjunction with other navigational techniques, such as dead reckoning and celestial navigation.

The sunstone is a relatively simple but effective navigational tool, and it is a testament to the ingenuity of the Viking sailors. The fact that the sunstone can still be used for navigation today is a testament to its enduring accuracy and effectiveness.