From the April 23, 2008 ARRL ARES E-Letter:

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The Maritime Mobile Service Net (MMSN) meets on 14.300 MHz and is composed of hams who serve and assist those in need of communications on the high seas.

According to its Web site <http://www.mmsn.org/>, the primary purpose of the net is for handling traffic from maritime mobiles. The network is recognized by the United States Coast Guard and has an excellent working relationship with that agency. The MMSN has handled hundreds of incidents involving vessels in distress, medical emergencies in remote locations and passing health and
welfare traffic in and out of affected areas.

They also work closely with the NWS and NHC by relaying weather reports from maritime stations.

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