Explanation: Modern Digital Selective Calling (DSC) radios are equipped with a dedicated "Distress Hot Key" for immediate emergency use. This button, often colored red and protected by a cover to prevent accidental activation, is specifically designed to transmit a pre-formatted digital distress alert with a single, sustained press (usually 3-5 seconds). This automated transmission occurs on VHF Channel 70 (the dedicated DSC calling channel) and instantly relays crucial information like the vessel's unique MMSI (Maritime Mobile Service Identity), current GPS position, and potentially the nature of the distress. This method is significantly quicker and more efficient than any other option. Making a "MAYDAY" call on Ch-16 is for voice distress and is slower than an automated DSC alert. Ch-70 is for digital signaling only, not voice. While some radios might offer a "Distress" option through a menu, the hot key bypasses menu navigation, making it the fastest method.