Marine Radio Service
Marine Radio operates under 47 CFR Part 80.
Marine radio operates in the VHF band and with an internationally agreed plan of about 80 channels most of which are simplex but some are duplex, mostly for ship-to-shore communications.
The Marine Band also operates in a number of HF frequencies. The full list, including HF, are in [Part 80, subpart H].
FCC rules explicitly prohibit use of a Marine radio while on land with the exception of public safety in Alaska, or with a special exemption from the US Coast Guard and FCC [§80.15]. In the U.S. the Coast Guard monitor channel 16 and other channels and have considerable direction finding capabilities to locate ships in distress.
Aviation Radio Services
Aviation Services operate under 47 CFR Part 87.
Aircraft stations can be either Ground Stations or Aircraft Stations. An aircraft station is licensed by rule and does not need an individual license. A station operator must hold a commercial radio operator license or permit [§87.89(a)] except as listed in paragraph (d).