Actually, MARSEC Levels are as follows:

Maritime Security (MARSEC) Level means the level set to reflect the prevailing threat environment to the marine elements of the national transportation system, including ports, vessels, facilities, and critical assets and infrastructure located on or adjacent to waters subject to the jurisdiction of the U.S.

MARSEC Level 1 means the level for which minimum appropriate protective security measures shall be maintained at all times. This is the normal operating MARSEC level for the port and is equivalent to YELLOW (Elevated) in the Homeland Security Advisory System.

MARSEC Level 2 means the level for which appropriate additional protective security measures shall be maintained for a period of time as a result of heightened risk of a transportation security incident. This is equivalent to ORANGE (High) in the Homeland Security Advisory System.

MARSEC Level 3 means the level for which further specific protective security measures must be maintained for a limited period of time when a transportation security incident is probable or imminent, although it may not be possible to identify the specific target. This is equivalent to RED (Severe) in the Homeland Security Advisory System.