In addition to distress signals like mayday and pan-pan, most vessels, especially passenger ships, use some emergency signals to internally alert the crew onboard, and in some cases also the passengers. These can be in form of blasts on alarm bells, sounding the ship's whistle or code names paged over the PA system.

• Mr. Skylight paged over the PA system is an alert for the crew onboard and means there is a minor emergency somewhere.
• Mr. Mob means man overboard. Man overboard can also be signaled with three prolonged blasts on the ship's whistle and general alarm bell
• Code Blue usually means a medical emergency.
• Abandon ship, seven or more short blasts on the ship's whistle and general alarm, followed by one long blast.
• Fire and emergency, continuous ringing of the general alarm bell for ten seconds and a continuous sounding of the ship's whistle for ten seconds.