Which describes the first digital sea area under GMDSS?

The first digital sea area under the Global Maritime Distress and Safety System (GMDSS) is best described as the distance from shore where a VHF radio can receive signals from at least one shore station, typically extending to about 20 nautical miles. This area is essential for ensuring that vessels operating close to shore can maintain reliable communication, especially for distress and safety purposes.

In the context of GMDSS, this VHF coverage is crucial because it allows ships to communicate effectively with shore facilities, enhancing maritime safety by facilitating timely interventions in emergencies. VHF radios are widely used for short-range communication and are critical when vessels are operating within this vicinity.

The other options relate to different operational scopes and technologies within the GMDSS framework. For instance, the use of MF-DSC radios pertains to medium-frequency communication that covers broader distances and is categorized as part of the GMDSS, but it describes a different area of coverage. The options concerning areas outside of specified latitude ranges and satellite communication address further advancements in maritime communication that do not pertain directly to the first established digital sea area defined by VHF radio capabilities.