A smartphone marine vessel location system utilizes global positioning to determine the location and trajectory of marine vessels. When two marine vessels have a trajectory that will bring the vessels within a warning zone a trajectory alert is activated and when the two vessels enter into a warning zone, a collision warning is activated. An App on the smartphones may produce a display showing the location of the marine vessels and may produce the alerts when required. The smartphone may also communicate with other navigational system on the marine vessel to produce a display and alerts, such as through Bluetooth. The location of marine vessels may be acquired through the App, through a crowd-sourcing application, and/or through a carrier sourced location.