What does a red bouy with a 4 mean?

A red buoy with the number 4 typically indicates a specific navigational marker in maritime contexts, often used in the U.S. and other countries that follow similar buoyage systems. It serves as a channel marker, helping mariners identify safe passage and navigate through waterways. The number 4 signifies its position in a series of markers, usually denoting that it is on the right side of the channel when returning from the open sea. This system aids in safe navigation and helps prevent groundings and collisions.