It’s not often that you get to celebrate a sesquicentennial, but that’s just what the National Geospatial-Intelligence Agency did this fall at its Springfield, Virginia, campus. For 150 years, the Notice to Mariners has kept navigators and shipmasters informed with the most current navigational information. The average observer would be forgiven for not knowing the notice even exists. Vessels navigating safely rarely make headlines. Notice to Mariners have neither dramatic moments nor hair-raising adventures. Yet for 150 years, every American ship officer, reflecting on a safely completed voyage, owes a piece of that to the men and women behind the Notice to Mariners. Today, NGA’s Maritime Safety Office has the responsibility to provide accurate charts and publications, including the Notice to Mariners, to support safety of navigation.