The correct answer is B) currents in various locations. The Sailing Directions, published by the National Geospatial-Intelligence Agency, provide detailed information on navigational conditions in various waterways, including current patterns, tidal information, and other factors that mariners need to be aware of when planning and conducting voyages. This information is essential for ensuring safe navigation, particularly in areas with complex current flows or tidal influences. The other answer choices are incorrect because they do not accurately describe the primary content of the Sailing Directions. The Sailing Directions do not directly address required navigation lights (A), casualty reporting procedures (C), or lifesaving equipment standards (D), which are typically covered in other regulatory and reference materials.