Marine two-way radios provide push-to-talk, real-time voice communication to collaborate, coordinate action, and share information or alerts while traveling on watercraft or monitoring waterways from land stations. They operate on Maritime Mobile Service (MMS) to transmit and receive messages in specific ranges of the very high frequency (VHF) band. Their channels are dedicated to specific types of communications, such as distress calls and passage confirmation. Marine radios require a license for land stations, commercial watercraft, and vessels traveling in international waters but not for recreational watercraft that remain in domestic waters.